QUESTION: The Gemara relates that a certain man prohibited his wife from going up to Yerushalayim for the festival. She violated his word, and he came before Rebbi Yosi to have his Neder annulled.
The Rishonim point out that Rebbi Yosi lived after the Churban of the Beis ha'Mikdash. Why, then, did the woman want to go to Yerushalayim for the festival?
(a) The ROSH and SHITAH MEKUBETZES write that a Jewish community has remained in Yerushalayim since the time of the Churban. In public lectures before and during the each festival, the Chachamim of Yerushalayim would teach the Halachos of the festival (like the "Shabsa d'Rigla" mentioned in Berachos 17b, 30a, and elsewhere). People would ascend to Yerushalayim at the time of the festival to hear the public lectures. The men would come to learn Torah and ask their Halachic questions to the Chachamim, and the women would come to see the glory of the Torah. (See also MAHARATZ CHAYOS here.)
(b) The Tosefta (Nedarim 5:1) relates that the person made a Neder to prohibit his wife "from ascending to Yerushalayim," with no mention of the festival. This Girsa implies that his wife wanted merely to go to Yerushalayim because of the city's great holiness (as the Mishnah discusses in Kesuvos 110b); she was not going specifically for the festival.
(c) RAV HAI GA'ON writes that it was a meritorious practice in his day to ascend to Yerushalayim at the time of the festivals. (See a full summary of the sources for such a practice in IR HA'KODESH V'HA'MIKDASH of RAV YECHIEL MICHAL TUKACHINSKY zt'l.)


OPINIONS: The Gemara explains that the Mishnah means that a person may make a condition on Rosh Hashanah (or Yom Kippur) that any Neder he makes in the coming year should be null and void. If he makes a Neder during the year without remembering his stipulation, the Neder does not take effect.
The Gemara's explanation seems similar to the practice of reciting "Kol Nidrei" on Yom Kippur eve. Is this Gemara the source for the recitation of "Kol Nidrei"?
(a) The RAN in the name of RABEINU TAM writes that this indeed is the source for the recitation of "Kol Nidrei." Accordingly, "Kol Nidrei" should be recited in the future tense and not in the past tense, since it is a declaration of annulment of the coming year's Nedarim and not the past year's Nedarim.
(b) The ROSH (3:5) writes that the purpose of "Kol Nidrei" is to annul Nedarim made during the previous year. He proves this from the fact that it is recited three times, just as a Chacham declares "Mutar Lach" three times when he annuls one's Neder. He cites further proof from the fact that it is followed by the recitation of the verse, "v'Nislach l'Chol Adas Bnei Yisrael..." -- "May it be forgiven for the entire congregation of the people of Israel...," which implies a pardon of the transgressions of the past.
The Rosh questions, however, how Nedarim may be annulled in such a manner. The annulment of Nedarim requires a Beis Din of three men. Moreover, it requires a Pesach (grounds for regret for having made the Neder)! The Rosh answers that since everyone recites "Kol Nidrei" quietly with the Chazan, they all serve as a Beis Din of three men (Hedyotos) to annul each other's Nedarim. It is not necessary to find a Pesach because it is assumed that everyone regrets (Charatah) the Nedarim which he made.
Some explain that this procedure of Hataras Nedarim was chosen to commence the services of the holiest day of the year in order to arouse a spirit of repentance. Teshuvah is unique in that it retroactively uproots the sins of one's past. The only other act done in the past which can be uprooted retroactively is a Neder, which can be uprooted through Hataras Nedarim. Therefore, it is appropriate to begin the day of repentance with such a declaration.
(c) The ME'IRI writes that "Kol Nidrei" does not serve to annul ordinary Nedarim. Rather, it serves to annul the Nedarim and Charamim made by the community, the Tzibur, as a whole. The removal of such Nedarim required neither the Hatarah of a Chacham or Beis Din nor Charatah, and thus it may be done through the recitation of "Kol Nidrei."
(d) The NIMUKEI YOSEF explains that "Kol Nidrei" is not an act of Hataras Nedarim for either past Nedarim or future ones. Rather, it is a prayer to Hash-m that He not punish us for the past Nedarim that we made and transgressed.