Was the sciatic nerve prohibited at Sinai? I didn’t understand why you chose דווקא this problematic example.

In lesson 6 I brought Maimonides’ words in his commentary to the Mishnah at the end of chapter 7 of Chullin. See there.

So would someone who had not yet circumcised himself not be punished with karet?

Apparently not. Unless the Holy One, blessed be He, instituted a special karet for the command to Abraham. In any case, that would not be our karet, which was stated regarding the commandment given at Sinai.

And what is the meaning of God’s statement in prophecy to Abraham that whoever is not circumcised will be punished?

I don’t understand. Which statement?

In my opinion, Maimonides’ intention revolves around the reliability of Abraham’s prophecy—meaning that we are not obligated to believe Abraham, but only if Moses confirms it.

By “statement” I mean the warning that if his household would not be circumcised, they would incur karet.

Avi, I explained that if there is karet, then it was instituted separately for the command to Abraham. The command there was to all the members of his household and not specifically to his sons. So that is certainly a different command and a different karet. Otherwise there would have been no need to say it, since karet was already stated after the revelation at Mount Sinai—or conversely, there would have been no need to say it here.

Where is karet written in connection with Abraham?

See Genesis chapter 17.

I didn’t really understand: is the punishment of karet stated in the Torah anywhere regarding neglect of circumcision besides with Abraham?

You are right. I was mistaken here. For some reason I thought it was repeated. Indeed, the punishment appears only with Abraham. But Maimonides writes in his commentary to the Mishnah in Chullin there that the obligation to observe the commandment of circumcision is not because of the command to Abraham but because of the command at Sinai (there is also a command in the book of Leviticus; see below):

“And set your mind to this great principle stated in this Mishnah, namely their saying, ‘It was prohibited from Sinai,’ and that is: you must know that everything from which we refrain or that we do today, we do only because of God’s command through Moses, not because God commanded it to the prophets who preceded him. An example of this is that we do not eat a limb from a living animal not because God prohibited a limb from a living animal to the descendants of Noah, but because Moses prohibited a limb from a living animal to us through what he was commanded at Sinai, namely that a limb from a living animal remain prohibited. Likewise, we do not circumcise because Abraham circumcised himself and the members of his household, but because God commanded us through Moses to circumcise as Abraham, peace be upon him, circumcised. And likewise with the sciatic nerve: we do not follow the prohibition of our patriarch Jacob, but the command of Moses our teacher. Do you not see that they said that 613 commandments were stated to Moses at Sinai, and all these are included among the commandments.”

It seems to me that the punishment does not appear again in the Torah, and perhaps it is included in the principle in Sanhedrin 59 that anything that was said and not repeated at Sinai was said only to Israel. Although that is stated about something said to the descendants of Noah, whereas here we are speaking about something said to Abraham. But it stands to reason that if something said to Abraham was not repeated, it is no less so than something said to the descendants of Noah and not repeated.
Still, when Maimonides describes the order in which the commandments were given in Laws of Kings 9:1, he writes that Abraham was commanded regarding circumcision. But in light of what he writes in Sefer HaMitzvot and in his commentary to the Mishnah, it seems that his intention is that the obligation to observe it is only because the matter appears in the Torah given at Sinai (and perhaps by the appearance of the verses spoken to Abraham, not necessarily specifically the verses in Leviticus), and not because of the command to Abraham.
If so, then the karet punishment stated with Abraham was said for its own time, and only from the point that it was repeated at Sinai was it applied to Israel for their commandment.

On the same topic: you brought Maimonides in Laws of Kings regarding a Noahide, and explained it in accordance with Maimonides in Laws of Idolatry, “one who worships out of love,” etc.—that is, that observing commandments counts only if it is done out of obedience to a divine command. You argued that Maimonides in Chullin is not saying the same thing, and corresponds to a different principle. It should be noted that in Laws of Kings Maimonides emphasizes that a Noahide is considered one of the pious of the nations of the world only if he observes the commandments because “they were written in the Torah through Moses.”
And seemingly it would have been enough if he observed the commandment because he thinks God commanded it, regardless of where He commanded it. So it seems that it really does correspond to Maimonides in Chullin, even though in principle your point seems plausible.

That is exactly what I said. He ties both principles to Sinai, and still these are different principles: in Chullin this is the basic norm, and in Laws of Kings this is a definition of a commandment-act. And as stated, both depend on the command at Sinai.

It is still a bit unclear to me why, for the purpose of defining something as a commandment-act, Maimonides requires that a Noahide act specifically because Moses commanded it. Seemingly, a commandment-act draws its force from the fact that it is prescribed by God.

But not as a commandment of the Jewish religion. The revelation of the Holy One, blessed be He, as a commanding God was at Sinai. That is the basic norm. Observing His commandments that did not come through Sinai could also lead to Christianity or Islam. They too claim that they observe the commandments of that same God.

That would make sense if Maimonides were discussing only the law of a resident alien, but he is also addressing the issue of their share in the World to Come. So on what basis would one say that fulfillment of a commandment as such is only when the person does it because Moses commanded it? What is the logic?

After all, he is doing it because, in his view, God commanded it.

I already answered that. I don’t understand what is new in the question.

Let me sharpen it: if you performed a commandment that does not exist and that God never commanded at all, then clearly that is not a commandment-act. But when God did command it and established it as a religious act, why should it matter to us whether the person thinks Abraham transmitted it or, alternatively, Moses? That seems like a non-essential detail. Granted, in Chullin Maimonides is speaking about the source of obligation, so one can understand that only Moses’ prophecy obligates. But to say that it is not a commandment-act at all if I do not know that Moses said it—that is not clear, and a source is needed for Maimonides.

We are talking about the commandments given at Sinai. If you perform a commandment because, in your opinion, the Holy One, blessed be He, commanded you personally, or through Shimon Cohen from Ashdod, then you are not performing a commandment but inventing commandments. I do not understand the difficulty.

I’ll try again, please: why is a Noahide who does not steal because God forbade it to Noah—which is in fact true—and who does not believe that he is forbidden to steal specifically because Moses said so, considered someone who invents a commandment? After all, he really is commanded not to steal, by force of God’s demand that he act that way, and not because of Moses, who serves only as the vehicle for informing us that such a prohibition exists and is not the source of authority.

Because if he does it by force of a command that is no longer valid, that is like doing it because of the command of Shimon Cohen from Ashdod. That command given to Noah no longer exists. In the background here is the claim that part of the essence of a commandment is responding to the command—that is, not only what you do, but also why.