What Do Gid Ha-Nasheh and Chametz on Passover Have in Common? The Historical Origin of These Dietary Prohibitions and the Implications for Their Halachic Characterization

With G-d’s help

Sinai — 5769 (2009)

Michael Avraham

R.M. (lecturer) at the Center for Advanced Torah Studies, Bar-Ilan University

052-3320543

mikyab@gmail.com

Disclaimer: This article was translated from Hebrew using AI (ChatGPT 5 Thinking), so there may be inaccuracies or nuances lost. If something seems unclear, please refer to the Hebrew original or contact us for clarification.

Introduction

The prohibition of eating chametz is mentioned in the Torah in several places. In all of them, se’or (sourdough) and chametz (leaven) are mentioned interchangeably, and at first glance it would seem that se’or and chametz are synonyms for the very same prohibition.

For example, Exodus 12:15:

“Seven days you shall eat unleavened bread; but on the first day you shall remove se’or from your houses, for whoever eats chametz shall be cut off—that person—from Israel, from the first day until the seventh day.”

And likewise there, 12:19:

“Seven days se’or shall not be found in your houses; for whoever eats something leavened (machmetzet)—that person shall be cut off from the congregation of Israel, whether a sojourner or a native of the land.”

In these two sources, the removal pertains to se’or while the eating pertains to chametz (machmetzet).

In another source we find (Exodus 13:7):

“Unleavened bread shall be eaten for seven days; and no chametz shall be seen with you, and no se’or shall be seen within all your borders.”

Here, both se’or and chametz are presented as a prohibition of “being seen.”

But as is known, se’or is unfit for consumption—indeed not even fit for a dog to eat.[1] Thus we find in Tosefta Beitzah 1:7 (see also Hagahot Maimoniyot, Chametz 1:2):

“What is ‘se’or’ that makes other things ferment? ‘Chametz’ that became leavened through something else. From when is it called ‘se’or’? From when it becomes unfit even for a dog.”

Now, foods that are not fit for human consumption (even if fit for a dog) are not prohibited by the usual biblical eating prohibitions (see Rambam, Hilchot Ma’achalot Assurot 14:11). Moreover, later authorities wrote that eating something unfit for consumption is even “lighter” than eating in an atypical manner—where one is also exempt—because here not only is there no act of normal eating, but the prohibited object is not a cheftza (halachic object) of prohibition at all (see Chavvat Da’at §103 and others).[2]

If so, it is unclear why the Torah forbids se’or as well, even though it is unfit for eating. How can there be a prohibition of eating something that is not edible? Several later authorities noted this (see Achiezer, YD §11:3; and Minchat Chinukh mitzvah 19, citing the P’ri Megadim; and the notes in the Jerusalem Institute edition there). Some tied it to a special scriptural novelty, that the verse explicitly forbade se’or as well, but this still requires explanation. Moreover, regarding chametz too: one who eats chametz that is unfit for consumption is exempt.[3] In what way, then, does the law of se’or differ from ordinary chametz that is unfit for eating?[4]

In this article I will propose a possible explanation, primarily according to the Rambam, and point out parallels between the prohibition of chametz and that of the sciatic nerve (gid ha-nasheh). I will distinguish between three types of eating prohibitions, and note several halachic ramifications of this distinction.

The Beitzah Sugya: Se’or and Chametz

The opening Mishnah of Beitzah records the dispute between Beit Shammai and Beit Hillel:

“Beit Shammai say: for se’or the measure is a kezayit (olive-bulk), and for chametz—a k’kotevet (date-bulk). Beit Hillel say: both this and that are a kezayit.”

Simply understood, the dispute concerns the prohibition of eating chametz, and the question is whether the measure for se’or is the same as or different from the measure for ordinary chametz.

And in the Gemara 7b we find:

“What is Beit Shammai’s reasoning? If so, let the Torah write ‘chametz’ and not require ‘se’or,’ and I would say: if for chametz—whose leavening is not severe—the measure is a kezayit, then for se’or—whose leavening is severe—all the more so. Why then did the Torah write ‘se’or’? To tell you: the measure of this is not like the measure of that.”

According to Beit Shammai, had Scripture written only “chametz” and not “se’or,” we would have derived se’or by an a fortiori argument, since its leavening is stronger than that of ordinary chametz. From the fact that the word “se’or” appears, they infer that the measures differ between chametz and se’or. Why is chametz a k’kotevet and se’or a kezayit? Apparently because, by Beit Shammai’s own kal va-chomer, se’or is the more stringent prohibition (its leavening is more intense), and therefore a smaller measure suffices to incur liability for eating it.

What do Beit Hillel answer? The Gemara states:

“And Beit Hillel: both verses are needed. For if the Torah had written ‘se’or,’ I might have said: because its leavening is severe; but chametz, whose leavening is not severe—say it is not [forbidden], so ‘se’or’ is needed. And if the Torah had written ‘chametz’—because it is edible; but se’or, which is not edible, say it is not [forbidden], so ‘chametz’ is needed.”

Beit Hillel disagree with Beit Shammai and argue that there is a refutation of Beit Shammai’s kal va-chomer from chametz to se’or, because se’or is not fit to be eaten. Therefore, had the Torah not written the prohibition of se’or, I might have thought only chametz is forbidden to eat and se’or is not—since se’or is not edible (as with other Torah prohibitions of benefit, which do not apply when not eaten in the normal way and when the item is inedible).

It seems Beit Shammai are not troubled by the fact that se’or is inedible. Note that even according to Beit Hillel—halacha—se’or is forbidden to eat since the Torah forbade it, but in their view this is a result of the verse’s explicit prohibition. Were it not for the verse, we would have assumed chametz is like all other Torah food prohibitions and is forbidden only when edible. But according to Beit Shammai, this would be true even without the verse—if the Torah had not written se’or and had written only chametz, Beit Shammai think we would derive that se’or is also prohibited to eat by kal va-chomer. Why not take into account that it is unfit for eating, like all Torah food prohibitions? Even with Beit Hillel there is room to ask: granted, we learn it from the verse—but why is that so? In what way does the prohibition of eating chametz differ from other food prohibitions in the Torah? Moreover, how does se’or differ from other chametz that is not edible?

Afterwards, the Gemara rejects the possibility that the dispute concerns eating, and establishes it with respect to the obligation of removal (bi’ur):

“Do Beit Shammai not accept Rabbi Zeira? For Rabbi Zeira said: ‘Scripture opened with “se’or” and concluded with “chametz” to teach you: this is se’or, this is chametz!’ — Concerning eating, everyone agrees; they disagree regarding removal. Beit Shammai hold: we do not derive removal from eating; Beit Hillel hold: we do derive removal from eating. It was also taught likewise… This is the dispute between Beit Shammai and Beit Hillel: Beit Shammai say ‘se’or is a kezayit and chametz a k’kotevet,’ and Beit Hillel say: ‘both are a kezayit.’”[5]

In conclusion, the dispute of Beit Shammai and Beit Hillel concerns the measure for the obligation of removal of chametz; as for eating, there is no dispute—by all opinions both se’or and chametz are measured by a kezayit.

Again, note that Beit Shammai’s view was not rejected on the grounds that one cannot ignore the inedibility of se’or. This point did not trouble the Gemara; what rejected that reading of the dispute was only Rabbi Zeira’s exposition. This sharpens the fact that the Gemara’s initial assumption remains in need of explanation even after the conclusion: why is the Gemara untroubled by the irrelevance of edibility to the prohibition of eating chametz?

Rambam’s Halachic Ruling

The Rambam, in Hilchot Chametz u’Matza 1:2, records the Gemara’s conclusion. To see the context, here are his first two laws in those halachot:

(1) Whoever eats a kezayit of chametz on Pesach—from the beginning of the night of the fifteenth until the end of the twenty-first of Nisan—intentionally, is liable to karet, as it says (Exod. 12): “for whoever eats chametz… shall be cut off”; unintentionally—he must bring a fixed sin-offering. The same applies to one who dissolves it and drinks [it].

(2) Chametz on Pesach is prohibited in benefit, as it says (Exod. 13): “No chametz shall be eaten”—i.e., there is to be no permission of eating for it. One who leaves chametz in his possession on Pesach—even if he did not eat it—transgresses two prohibitions, as it says (Exod. 12): “No se’or shall be seen for you in all your borders,” and it says: “Se’or shall not be found in your houses.” And the prohibition of chametz and the prohibition of se’or—by which they leaven—are one and the same.

From the end of his 1:2 it is clear that the Rambam views the prohibitions of chametz and se’or as the same prohibition. It would appear this applies both to eating (which is undisputed) and to removal (for the law follows Beit Hillel).

His wording also suggests, as noted above, that there is here a special scriptural decree (gezerat ha-katuv) that se’or is forbidden to eat even though it is inedible. His words also imply an explanation: since se’or is that with which other doughs are leavened, it certainly falls under the rubric of “chametz.” In other words, the difference between ordinary inedible chametz and se’or is that ordinary inedible chametz no longer carries the name “chametz,” whereas se’or—by which one leavens other doughs—does carry the name “chametz” despite being inedible. That which causes leavening surely itself bears the name “chametz.”

There seems to be an analogy here to what we find in Hilchot Shabbat 9:14, where the Rambam disagrees with the Ra’avad about preparing dye with respect to the labor of dyeing (tzove’a):

“One who makes the ‘eye of the dye’ (i.e., the concentrated dye base) is liable as a derivative of dyeing. How so? For example, one who puts vitriol into gall-water so it all becomes black, or woad into saffron water so it all becomes green—and similarly the like. The measure is enough to dye a thread four handbreadths long.”

Ra’avad’s gloss: ‘Dyeing—how so? For example, one who puts vitriol into gall-water and the waters become colored—’ I am astonished: for ‘cooking dyes’ from which we derive cooking (Shabbat 74) should also make him liable for dyeing the water. And I would not have thought one is liable for dyeing until he actually dyes an object in which the dyeing is completed; but coloring water, when the color is not for the water itself, should not [incur liability]… And soaking ink and dyes comes for kneading, not for coloring the water…”

The Rambam holds that preparing the dye base is included in the labor of dyeing, since the dye is the instrument with which one dyes.[6] This is analogous to his view here: since se’or is what leavens other doughs, it evidently bears the name “chametz.”[7]

Still, this requires clarification. Even if this explains that se’or bears the name “chametz,” it does not yet resolve the fundamental difficulty: how can such chametz be prohibited to eat if it is inedible? Why is it sufficient that se’or be termed “chametz” to explain its prohibition of eating? After all, even if it bears the name “chametz,” one would have expected it to be permitted like other inedible items. Especially according to Beit Shammai, who would have prohibited se’or even without the Torah’s explicit novelty.

To understand this, we will first present a general discussion of Torah food prohibitions and then return to the prohibition of chametz.

The Relationship Between an Eating Prohibition and a Benefit Prohibition

A well-known dispute among the Amoraim appears in Pesachim 21b regarding the relationship between prohibitions of eating and prohibitions of benefit (issur hana’ah) in the Torah:

“Chizkiyah said: From where do we know that chametz on Pesach is forbidden in benefit? As it says (Exod. 13): ‘lo ye’akhel chametz’—it shall not be eaten—meaning: there shall be no permission of eating (i.e., of benefit) for it. The implication is: only because Scripture wrote ‘lo ye’akhel’; had it not written ‘lo ye’akhel,’ I might have said the verse implies a prohibition of eating, but not necessarily a prohibition of benefit. And this disagrees with Rabbi Avahu, for Rabbi Avahu said: everywhere that it says ‘lo tokhal,’ ‘lo tokhlu,’ or ‘lo ye’akhel,’ both a prohibition of eating and a prohibition of benefit are implied, until Scripture specifies otherwise, as it did for a nevelah (carcass)….”

Rabbi Avahu holds that when the Torah states a prohibition using the language of eating (e.g., “you shall not eat”), it includes a prohibition of benefit—unless there is an explicit indication in the verse permitting benefit (as with nevelah, which may be sold to a non-Jew or given to a resident alien). Chizkiyah, by contrast, does not accept this rule and requires a separate source for a benefit-prohibition. For chametz he derives it from the passive formulation “lo ye’akhel” (“shall not be eaten”), rather than the active “do not eat.” Rashi explains that “shall not be eaten” implies an interdiction that chametz be eaten by anyone—even by a gentile, who is not himself bound by the eating prohibition—thus indicating that the Jew’s benefiting (e.g., via sale proceeds) is proscribed. According to Rabbi Avahu, no special derivation would have been needed; even “do not eat” would imply no benefit.

The Rambam’s View of Eating Prohibitions

In Hilchot Ma’achalot Assurot 8:15, the Rambam rules like Rabbi Avahu:

“Wherever the Torah says ‘lo tokhal,’ ‘lo tokhlu,’ ‘lo yokhlu,’ or ‘lo ye’akhel,’ both a prohibition of eating and a prohibition of benefit are implied, until Scripture specifies otherwise as it did for a nevelah (‘you may give it to the stranger in your gates and he shall eat it’) or for cheilev (‘it may be used for any work’), or until it is clarified by the Oral Law that benefit is permitted—as with swarming things, blood, a limb from a living animal, and the sciatic nerve—though they are forbidden to eat.”

In his Commentary to the Mishnah (Kereitot 3:4), the Rambam adds a striking implication of Rabbi Avahu’s principle:

He explains that the prohibition of benefit in meat-and-milk (basar be-chalav) is not an independent interdiction added atop a separate eating-prohibition; rather, since the Torah forbade eating it, benefit follows from that general rule (“anything the Torah forbids to eat, it forbids to benefit from, unless specified otherwise”). Consequently, “no prohibition rests upon a prohibition”: if the meat component were already prohibited (e.g., nevelah), the added prohibition of benefit would not “land” anew as a distinct overlay. He contrasts this with sacred fat of offerings, where a new dimension (misappropriation) creates liability for benefit.

He elaborates further in Sefer Ha-Mitzvot (Negative Command 187) and the Sefer Ha-Chinukh (mitzvah 113): benefit is subsumed under eating where the Torah used eating-language; hence we do not count “benefit” as a separate command for each food prohibition.

At the end of that discussion the Rambam explains (based on Pesachim 25a) why the Torah did not phrase meat-and-milk as “do not eat” and instead expressed it via “do not cook”: because in meat-and-milk the prohibition of eating is not the usual “benefit-via-eating,” but rather an interdiction of the act of eating itself—even without enjoyment; thus one is liable even if he did not derive benefit (e.g., it was scalding hot).

This yields a further inference, which the Rambam treats as obvious: where a prohibition is expressed in ordinary eating-language, the target is enjoyment by way of eating (serving as an example of all benefit). Where phrased otherwise, the target is the very act of eating the forbidden item, even absent enjoyment. Therefore, eating without enjoyment remains prohibited in those cases.

This distinction hints at the nature of the chametz-eating prohibition. There, too, we saw that eating se’or—though inedible—is forbidden. Let us now return to our sugya and develop this.

The Rambam’s Underlying View of the Chametz Prohibition

We saw that in Hilchot Chametz u’Matza 1:2 the Rambam cites Chizkiyah’s derivation from the passive “lo ye’akhel” for the benefit-prohibition of chametz. Commentators wondered: if the Rambam rules like Rabbi Avahu, why did he need Chizkiyah’s derivation here? The Kessef Mishneh suggests the Rambam preferred the explicit verse, though strictly speaking he did not need it.

A more compelling explanation emerges from his broader approach: chametz on Pesach is a prohibition of the act of eating, not primarily of benefit via eating—akin to meat-and-milk. Consequently, you cannot infer a benefit-prohibition from the eating-prohibition; a distinct source (Chizkiyah’s “lo ye’akhel”) is required.

What is the source of this approach? Seemingly, the sugya in Beitzah cited above: per Beit Hillel (and the halacha), se’or is forbidden to eat despite being inedible. The Rambam understands the reason to be that chametz-eating is an act-prohibition: performing the act of eating upon something designated “chametz,” even without enjoyment.

Beit Shammai go further: they maintain this would follow even without an explicit verse about se’or, by kal va-chomer. How can they assume that? Because here the prohibition does not stem from an inherent loathsomeness of the substance (as with treif foods). Chametz is not inherently loathsome—it is permitted before and after Pesach. Rather, the Torah commanded a commemorative practice—not to perform the act of eating upon chametz—as a reenactment of the Exodus. The prohibition thus addresses the act, not the benefit (we will see a parallel with gid ha-nasheh).[8]

We can now appreciate the Rambam’s sequence in 1:1–2. First, he presents the act-prohibition of eating chametz (1:1). Separately (1:2), he establishes the benefit-prohibition—requiring an independent source (Chizkiyah). Finally, he explains why se’or is included: since it leavens other doughs, it is certainly called “chametz,” and the act-prohibition of eating applies to it even without enjoyment. The only question is whether it carries the name “chametz”—to which the Rambam answers yes (much as “preparing dye” counts as dyeing).

Why, then, is ordinary chametz that is inedible exempt? Because such chametz no longer bears the name “food” and loses the designation “chametz” for eating purposes; one who eats it has not performed the act of eating chametz. Se’or is different: its very inedibility stems from its leaven-strength, the essence of “chametz-ness,” so it retains (even heightens) the name “chametz.”[9] Hence the exemption for inedibility in standard food-laws does not apply here.

In typical food prohibitions, when an item becomes repulsive one is exempt both because there is no enjoyment and because the item loses its identity as the forbidden substance. With chametz, enjoyment is irrelevant to the eating-prohibition; exemption arises only when the item loses the name “chametz.” The practical difference is precisely se’or: it retains the name “chametz” (it leavens), thus eating it violates the act-prohibition even without enjoyment.

The Prohibition of Eating the Sciatic Nerve (Gid Ha-Nasheh)

Another prohibition given as a historical commemoration is gid ha-nasheh. Scripture itself states that its reason is “therefore the Israelites do not eat the sciatic nerve… for he touched Jacob’s hip socket” (Gen. 32:33).

A further resemblance to chametz: gid is inedible. In Pesachim 22a (immediately after the Chizkiyah/Rabbi-Avahu discussion) the Tannaim debate whether tendons impart taste; the upshot affects whether gid is forbidden in benefit. The baraita records Rabbi Yehudah (tendons do impart taste → benefit permitted) and Rabbi Shimon (do not impart taste → benefit forbidden), aligned respectively with Chizkiyah and Rabbi Avahu.

If, per Rabbi Shimon, gid is inedible, why is eating it prohibited at all? By our approach, because—like chametz—this is an act-prohibition commemorating an event, not a loathsomeness-based food ban. Thus the act of eating is proscribed on something carrying the name “gid,” irrespective of enjoyment.

Most poskim rule “tendons do not impart taste.” The Rambam (Ma’achalot Assurot 15:17; and Shulchan Aruch YD 65:9) therefore excludes the gid from taste-based nullification (it doesn’t asser by taste). Yet in 8:14—just before ruling like Rabbi Avahu about food-bans generally—the Rambam rules:

“Gid ha-nasheh is permitted in benefit; therefore one may send a leg with the gid in it to a gentile, handing it over whole in a Jew’s presence (its place is recognizable). But if the leg is cut up, he should not give it in a Jew’s presence until the gid is removed, lest a Jew eat from it.”

The Ra’mach (and the Rosh) ask: but if the Rambam rules like Rabbi Avahu (eating → benefit), why permit benefit from gid? And since he rules “no taste” like Rabbi Shimon, wouldn’t Rabbi Avahu say benefit is forbidden? By our approach: for commemorative/“historical” prohibitions—gid and chametz—the eating-ban is an act-prohibition, not a benefit ban; hence you cannot infer benefit from eating (and need a separate source for chametz; for gid, no such source exists—therefore benefit is permitted). This coheres with the Beitzah sugya’s model (se’or).

Meat and Milk

We noted that meat-and-milk shares this “act-of-eating” character—though not for a historical reason. The Sefer Ha-Chinukh (mitzvah 92) offers a conceptual rationale: certain mixtures are metaphysically harmful or theologically problematic; the ban targets the act of creating/consuming the mixture, not its gustatory enjoyment. He supports this by noting liability even for eating without enjoyment—unlike standard food prohibitions—precisely because the core is the act (or “use”) of the mixed entity.

Accordingly, the Rambam writes (Ma’achalot Assurot 14:10):

“For all forbidden foods one is liable only when he eats them in the manner of enjoyment, except meat-and-milk and vineyard mixtures (kil’ei ha-kerem), since Scripture did not phrase them as ‘eating’ but forbade them in other terms (cooking/consecration), to prohibit them even without enjoyment.”

Why does he not list se’or and gid here? Later authorities infer that for these, the Rambam exempts when the act is not an act of eating (i.e., “not in the manner of eating”), but not simply because the object is inedible; se’or/gid are inedible by nature, yet eating them in the normal manner remains an act of eating and is forbidden. Thus: atypical manner exempts (no act of eating), but “inedible object” does not, so long as the item retains the name of the prohibition (as argued above).

Practically, then, we have three categories: (1) ordinary food-bans—prohibit enjoyment via eating (exempt if inedible or eaten without enjoyment); (2) meat-and-milk and kil’ei ha-kerem—prohibit use of the prohibited mixture (liable even without enjoyment or when not edible); (3) chametz and gid—prohibit the act of eating (exempt when not in the manner of eating, but not merely because the object is inedible, so long as its name/status remains).[11]

The Law of Half-Measure (Chatzi Shiur)

In Yoma 74a Rabbi Yochanan and Reish Lakish dispute whether “half-measure” is biblically forbidden (we rule like Rabbi Yochanan: yes). The Rambam (Chametz u’Matza 1:7) applies this to chametz:

“One who eats any amount of chametz itself on Pesach transgresses a biblical prohibition (‘lo ye’akhel chametz’), yet is liable to karet or a sin-offering only with a kezayit. One who intentionally eats less than a kezayit receives disciplinary lashes.”

Why cite a special verse here, if half-measure is biblically forbidden everywhere? The Kessef Mishneh is puzzled. By our approach, because chametz-eating is an act-prohibition, not an enjoyment-ban. Half-measure relies on the logic “fit to combine”—two half-portions together yield a full mezid enjoyment. But acts do not “add up”: two partial non-acts never form one completed act (you cannot “combine” two two-cubit throws on Shabbat into a four-cubit throw as an act). Thus, a special source is needed to ascribe biblical force to partial quantities in an act-type prohibition.[12][13]

The Maharlach (cited by the Melamed Le-Ho’il) suggests another angle: chametz differs from “eternal” food prohibitions because it is time-bound, hence needed its own verse for half-measure. Objection: Yom Kippur’s eating prohibition is time-bound, yet half-measure applies from the Yoma sugya itself. Our approach reconciles this: Yom Kippur is a benefit (affliction) framework—thus ordinary half-measure logic applies; chametz is an act framework—thus requires a special source.

Analogous reasoning appears for meat-and-milk: some wrote that its novelty limits half-measure. By our approach: again, it is an act-type prohibition; partial acts do not combine absent a special source.

A Special Prohibition on Chametz Mixtures

The Rambam, in Sefer Ha-Mitzvot, counts a distinct prohibition for eating a mixture containing chametz. The Sefer Ha-Chinukh (mitzvah 12) reports his view: if the mixture contains a kezayit of chametz within the time of eating half a loaf (kdei achilat pras), there is lashes (but no karet). The Ramban disagrees: if there is a kezayit of chametz within kdei achilat pras, that’s simply the standard chametz-eating prohibition (and would incur karet); the verse “kol machmetzet” teaches instead that even leavening caused by another agent is included.

The crux: the Rambam views the standard prohibition as an act of eating “something named chametz.” When the chametz is subsumed within a mixture, it is no longer the straightforward act of eating chametz; a special verse is needed to extend the act-prohibition to the act of eating a mixture containing chametz (with lashes, not karet). The Ramban views standard food-bans as enjoyment-bans: if you consumed a kezayit of chametz within kdei achilat pras, you enjoyed chametz and incur karet; no special verse is needed.

Nullification of Taste (Bitul Ta’am)

This also illuminates “chametz is not nullified on Pesach”—famously stringent. Nullification normally turns on taste, because ordinary food-bans target enjoyment of the forbidden taste. With chametz as an act-ban, once the Torah (per the Rambam) extended the name “chametz” to a mixture, taste is secondary: if it contains chametz, eating it is treated as the act of eating chametz. Still, many hold “chametz in the least amount” (mashehu) is rabbinic; on a Torah level, once the chametz loses the name of chametz via nullification rules, the act is no longer “eating chametz.” Chazal then decreed stringency due to Pesach’s nature and the act-type prohibition.

The Rambam (Ma’achalot Assurot 15:1–2) indeed rules that “leavening agents” (machmitzin) and “seasonings” (metablin) forbid in any amount—another reflection that the operative question is whether the item functions as “chametz” (leavens) rather than imparts taste.[18]

So too with gid: since the prohibition is act-based and the tendon imparts no taste, taste-nullification plays a different role. The Mishnah (Chullin 92b) sets a special benchmark (“like meat with turnip”)—understood by the Rambam in his commentary to refer not to taste of the gid, but to the point at which the identity “gid” is lost within the dish; then eating it is no longer the act of eating gid.[20] Some Rishonim similarly treat the tendon’s fat as non-prohibitive by taste, since its prohibition derives from the gid itself, whose law is act-based rather than taste-based.[21]

For meat-and-milk, the Chinukh (mitzvah 113) notes a unique stringency: when a piece becomes prohibited through meat-and-milk, “the piece itself becomes like a nevelah,” and can further prohibit other food as a whole piece—again echoing that the target is the mixed entity and its use/eating, not merely a forbidden taste.

Conclusion

There are several atypical eating prohibitions with practical consequences. Ordinary food-bans (we rule like Rabbi Avahu) prohibit enjoyment via eating. Meat-and-milk and kil’ei ha-kerem prohibit use of a problematic mixture (hence liability even without enjoyment or when inedible). Chametz (on Pesach) and gid ha-nasheh—rooted in commemoration—prohibit the act of eating upon items bearing the relevant names (“chametz,” “gid”). Therefore: they exempt when not in the manner of eating (no act), but not merely because the object is inedible—so long as its identity remains. From these distinctions flow ramifications for half-measure, nullification by taste, mixtures, and whether a benefit-prohibition follows from the eating prohibition (for these, it does not without a separate source).

[1] Although from the Rambam and Ra’avad (Chametz u’Matza 1:2) it appears some held that se’or might be fit for a dog—and in some cases even for humans. The commentaries there discuss at length.

[2] But see She’agat Aryeh §75, who argues the reverse: “not in the manner of enjoyment” is more stringent than “inedible.” We return to this point below.

[3] See Shulchan Aruch Orach Chayim 442:9 and commentaries. We will not enter the special cases of chametz nukshah and moldy bread.

[4] See Avnei Nezer OC §349 for extended analysis; see also Bi’ur Halacha ad loc., cited below.

[5] One may wonder, given the conclusion that the dispute concerns deriving removal from eating, what role the initial “se’or” redundancy played. Briefly: the debate over deriving removal from eating reflects divergent conceptions of removal—whether it is independent (Beit Shammai) or precautionary to avoid eating (Beit Hillel). See Lekach Tov (R. Yosef Engel), Klal 8, for development.

Thus, for Beit Shammai (regarding removal), edibility is irrelevant; the question is whether it is “chametz.” For Beit Hillel, edibility impacts removal (lest one eat it). Hence the earlier arguments echo here with respect to removal rather than eating.

[6] See also there 9:11 regarding laundering and stirring.

[7] See Achiezer YD §11 for a broad application of this logic (e.g., se’or of terumah and other prohibitions); and Avnei Nezer OC §349 on hyper-leavened chametz suitable to leaven other doughs.

[8] True, there is a separate benefit-prohibition for chametz; likely that too is part of the Exodus reenactment: as Israel did not benefit from chametz, so too we refrain.

[9] See Bi’ur Halacha 442:9, who links the Rambam’s view in 1:2 to this reasoning; he understands the Ra’avad to disagree.

[10] Cf. Avodah Zarah 66a (per R. Meir) treating diverse food-bans as a single class of prohibition, hence combinable.

[11] A potential tension with the Rambam arises from 14:11: he exempts when one eats repulsive/ruined foods—conflating “inedible” with “not in the manner of enjoyment.” For se’or/gid, however, the former does not exempt (as explained; and many note the Rambam there lists the “ruined” case en passant).

[12] All the more on the (minority) view of the Chacham Tzvi that half-measure exists only in eating prohibitions; but even those who dispute him concede that act-type prohibitions lack ordinary half-measure logic. See Sh’fat Emet to Shabbat 2a; and survey in Encyclopedia Talmudit, “Chatzi Shiur.”

[13] Compare half-acts in Shabbat labors done on objects (e.g., hotza’ah), discussed by the Melamed Le-Melech to Shabbat 18.

[14] See extensive sources in Encyclopedia Talmudit, “Chatzi Shiur,” nn. 503–525 and 445–448 (re: meat-and-milk).

[15] See Chullin 115b indicating meat-and-milk had a “time of permissibility” (as separate parts). Our use here is only as an indicator that the ban is not based on inherent loathsomeness.

[16] See Encyclopedia Talmudit, “Gid Ha-Nasheh,” n. 184, discussing challenges from Rashi and Meiri; and responsa Ktav Sofer YD §34. Our approach does not depend on eiver min ha-chai.

[17] See Encyclopedia Talmudit, “Chatzi Shiur,” nn. 444–466.

[18] A question remains: why does meat-and-milk have taste-nullification if it too is act-based? Answer: unlike chametz, we lack a verse extending the name to mixtures; therefore, where taste is nullified, the mixed entity is no longer treated as “meat-and-milk,” and the act is not an act upon that entity.

[19] See collated explanations in Encyclopedia Talmudit, “Gid Ha-Nasheh,” ch. 7.

[20] Notably, the Rambam omits this law in the Mishneh Torah. In his Commentary to the Mishnah he explains “like meat with turnip” as the point where the meat’s flavor registers in the gid—a sign the gid’s identity has been lost, which is our point here.

[21] The Rambam (15:17) nevertheless treats fat of the gid as rabbinic and subjects it to sixty—likely a lo plug policy for a derivative rabbinic extension.