Annulment after the Term of the Neder Expired

The Mishna states: If a person says: “Konam” (he forbids himself with a vow) that he will not taste any wine today, he is only forbidden from doing so until it gets dark.

Rabbi Yirmiyah says: When it gets dark, he must ask a scholar (to permit his vow). The Gemora asks: What is the reason for this? Rav Yosef answers: It is a decree, lest he confuse this case with a vow that he will abstain “for one day” (which the Mishna stated means that he is forbidden for twenty-four hours, not just until dark). 

The Acharonim ask: Why can’t he have the neder annulled before the night? Why must he wait for the night?

The Chasam Sofer answers: If he would have the neder annulled before the night, it would retroactively annul his neder. It would emerge that he had abstained for nothing. However, if he waits until the night to annul the neder, he has fulfilled his neder, since the term of his neder was for that day. It was only a stringency based upon a decree that he should have it annulled at night.

It is evident from the Chasam Sofer that he maintains that a neder cannot be annulled after its term has been completed. The Tosfos Ri”d holds that a neder can be annulled by a sage even after its term has expired.

Fasting Nowadays

The Ra”n asks on our custom of accepting to fast for one day, and immediately by nightfall, he is permitted to eat without petitioning a sage first. According to our Gemora, shouldn’t he be required to have the neder annulled because of Rav Yosef’s decree of “one day”?

The Ra”n answers: Everyone knows that the Chachamim instituted that the time for a fast is from morning until night. It is not similar to other nedarim, which do not have a set time. There, therefore, is no reason for a decree, for everyone understands that the halachos of nedarim and the halachos of fasting are distinct from each other.

The Rashba answers: The Gemora’s decree is only applicable in a case where he made a neder, saying, “Today, I will not drink wine,” which is similar to the case where he said, “I will not drink wine for one day.” There, we rule that he must have the neder annulled at nightfall, since it is similar to the case where he made the neder for “one day,” where he was permitted in the beginning of the day. However, regarding a fast, where one is forbidden to eat from the beginning of the day until its conclusion, there is no reason for any decree. One would easily think that the reason why we are lenient and allow him to eat at nightfall is because we were stringent upon him at the beginning of the day. When he makes the neder in middle of the day, and he was permitted up until then, we decree that he is required to petition a sage for annulment of his neder at nightfall.

The Rashba offers another answer: There is no place for Rav Yosef’s decree by a neder to fast, for even if one would make a neder to fast for “one day,” he will not be required to fast for twenty-four hours like by a different neder. Therefore, on a regular fast, he may begin to eat immediately upon nightfall.

The Yados Nedarim answers: This decree was never issued by a neder for a mitzvah. One who vows to fast is regarded as a mitzvah, as the Gemora refers to him as a kodosh.