Annulling Vows on Shabbos and Yom Tov - Shabbos 157a - Kol Nidrei
התרת נדרים בשבת ויו"ט
Annulling Vows on Shabbos and Yom Tov
The Gemara states here that vows may only be annulled on Shabbos is their anullment is l’tzorech Shabbos — essential for Shabbos — i.e., if those vows affect the proper observance of that specific Shabbos on which they are to be annulled.
Hence, Teshuvos HaRivash #394 has difficulty with our recitation of Kol Nidrei on Yom Kippur. The vows that we ask Hashem to annul in the Kol Nidrei do not affect the observance of Yom Kippur in any way. Why, then, is it permitted to recite the Kol Nidrei on Yom Kippur?
First, Rivash notes that the proper version of Kol Nidrei is the one in which it takes the form of a condition concerning future vows (from this Yom Kippur until next Yom Kippur). This is the case, despite the request for forgiveness that is included in the Kol Nidrei — as it would seem somewhat out of the ordinary to request forgiveness on sins not yet committed! (Rivash explains that this request pertains to possible cases in which a violation of a vow will be inadvertant, and that for which a person therefore might not realize he needs forgiveness.) He continues to prove from several aspects of the language used in Kol Nidrei that it is not an annullment, but rather a stipulation, or perhaps a request for atonement. Since that is the case, it is not an actual annullment, and therefore may be performed on Shabbos or Yom Tov.
He acknowledges that Rosh does maintain that Kol Nidrei pertains to past vows, and suggests that perhaps Rosh holds that since this annullment is meant to request atonement for violated vows, that it is tzorech ha’yom — i.e., essential for the day of atonement. Alternatively, the time for Kol Nidrei is generally fixed slightly before the actual onset of Yom Kippur — and thus the annullment is not taking place on Shabbos or Yom Tov.
(It is interesting to note that in the final analysis Rivash is opposed to the recitation of Kol Nidrei altogether, as he fears that its recitation leads people to regard taking vows lightly. He notes that in Catalonia it was never said at all.)