Q&A: Aleinu, Aleinu Leshabe'ach, Leshabe'ach to the Master, the Master of All, of All
Aleinu, Aleinu Leshabe'ach, Leshabe'ach to the Master, the Master of All, of All
Question
They say Aleinu Leshabe'ach at the end of Ma'ariv,
and then again at the end of Kiddush Levanah.
Is it appropriate to say it only at the end of Kiddush Levanah?
There once was a gabbai in a workers' minyan
who, when a fast day fell on Sunday and they read from the Torah, then when they returned the Torah scroll he said that "A psalm of David: The earth is the Lord's and all it contains" can count both for the Song of the Day and for returning the Torah scroll.
Does that work?
Answer
Aleinu Leshabe'ach has no clear source. In Shacharit it is ancient (in the Vitry Machzor), but in the other prayers it was inserted בעקבות the Ari. Therefore it's hard to speak of an obligation to say it, and simply speaking one can combine recitations. Still, the custom is to say it twice, and if there is no special reason one should not depart from the custom.
Discussion on Answer
Same as above.
Out of the four ancient prayerbooks we have in hand—those of Rav Amram Gaon, Rav Saadia Gaon, Maimonides, and Vitry—Vitry really is the most different from all the others, and if it has something different that's probably strong evidence of a late and non-binding addition. One example is that the Vitry Machzor innovated, based on Tractate Soferim, which only emerged at the end of the Geonic period, various odd additions to Kiddush Levanah that nobody ever knew or mentioned.
So the general question is whether there is any obligation regarding additions from Vitry, and whether that depends on their acceptance nowadays.
What does the Rabbi say?
Nothing is binding just because it appears in some prayerbook, no matter which one. There are obligations whose basis is an enactment accepted by an authorized institution, and there are customs whose force comes from their acceptance by the public. Each such type has its own parameters.
And regarding the Sunday Song of the Day + bringing the Torah scroll back to the ark,
can you do a 1+1 special?