Daf Yomi - Beitzah 19 - New Year's Resolutions

The Gemara cites the opinion of Rabbi Elazar the son of Rabbi Shimon who maintains that the reason the Torah mentions the festival of Sukkos is because Sukkos causes the prohibition of baal teacheir to be violated. Thus, if one pledged to bring an offering on the day prior to Sukkos, he will have violated the prohibition of baal teacheir if Sukkos passes and he has not brought the offering that he pledged to bring. One must wonder why Rabbi Elazar the son of Rabbi Shimon maintains that one violates the prohibition of baal teacheir even in the course of one festival. Perhaps the idea is that the Medrash states that subsequent to Rosh HaShanah and Yom Kippur, one is engaged in the performance of numerous mitzvos, and he does not even have time to sin. Thus, if one has the time to contemplate making a pledge that will require even more of him, the Torah mandates that he fulfill his pledge immediately, so that he will demonstrate that his pledge is truly sincere and not just a “New Years’ resolution.”