מתיב רבי אבא: ״קונם שאיני נושא לפלונית כעורה״, והרי היא נאה. ״שחורה״, והרי היא לבנה. ״קצרה״, והרי היא ארוכה — מותר בה. לא מפני שכעורה ונעשת נאה, שחורה ונעשת לבנה, קצרה ונעשת ארוכה — אלא שהנדר טעות. בשלמא לרב הונא דאמר נעשה כתולה נדרו בדבר: תנא תולה נדרו בדבר, ותנא נדר טעות. אלא לרבי יוחנן, דאמר כבר מת וכבר עשה תשובה, למה לי למתני תרי זימני נדר טעות? קשיא.
R' Abba raised an objection from a later Mishnah (66a): If one said: I will not marry ugly so-and-so as that is konam for me, and she is in fact beautiful, or if he called her black, and she is in fact white, or if he called her short, and she is in fact tall, he is permitted to her. Not because she was ugly and became beautiful, black and became white, or short and became tall, but rather, because the vow was mistaken from the outset. Granted, according to Rav Huna, who said that he is considered like one who makes his vow dependent on a matter, the Mishnah here taught the case of one who makes his vow dependent on a matter, and it taught there the case of a mistaken vow. But according to R' Yoḥanan, who said that the Mishnah here is referring to a situation where the dog had already died, or the father had already repented, why do I need the Mishnah to teach the halakha of a mistaken vow twice? The Talmud comments: This is difficult.