- Incident in which the lack of a pesach engendered one
The Gemara, beginning on Daf 22b, records several incidents where a pesach – an opening to a neder , could not be found, and this itself led to a pesach. When Rebbe Shimon bar Rebbe rejected the openings offered to him by the Rabbis, והוי מצטער רבנן משימשא לטולא ומטולא לשימשא – the Rabbis were pained, going back and forth between the sun and the shade , trying to find a valid opening. The Rishonim explain that the Rabbis deliberately pained themselves this way so that their frustration in trying to find an opening would be apparent to him. Rebbe Shimon bar Rebbe conceded that he would not have made the neder had he known it would cause them this frustration.
- The pesach of a wife transgressing her husband’s will
Abaye and his wife disagreed if her daughter from a previous marriage should marry his relative or hers. Abaye declared, תיתסרא הנאתי עלך אי עברת אדעתאי ומינסבת לה לקריבך - “My benefit shall be forbidden to you if you transgress my will and marry her to your relative,” but she nonetheless did so. Rav Yosef asked Abaye if he would have made the neder if he would have known that she would disobey him, and when Abaye said he would not have done so, Rav Yosef annulled the neder. The Gemara asks if such a pesach is accepted , since, as the Ran explains, the pesach is contradicted by the neder itself, as the whole point is that the neder should take effect if she disobeys? The Gemara quotes a Baraisa which states: מעשה באדם אחד שהדיר את אשתו מלעלות לרגל - There was a story with a man who made a neder forbidding his wife from going on pilgrimage, ועברה על דעתו ועלתה לרגל - and she transgressed his will and went on pilgrimage, and when Rebbe Yose asked him if he would have made the neder if he would have known she would disobey him, and he responded, “no,” Rebbe Yose annulled the neder.
- ובלבד שיהא זכור בשעת הנדר
The Gemara says that the next Mishnah is missing text and should read: והרוצה שלא יתקיימו נדריו כל השנה - One who wants all his nedarim to be ineffective the whole year, יעמוד בראש השנה ויאמר כל נדר שאני עתיד לידור יהא בטל - should stand on Rosh Hashana and say, “Every neder I will make should be null,” ובלבד שיהא זכור בשעת הנדר - and this is effective, provided that he remembers his declaration at the time of the neder. When the Gemara objects, saying that if he recalls his stipulation and ignores it, he thereby uprooted it, and the neder should be valid, Abaye answers that the Mishnah should be rendered in the reverse, that only if he does not recall his disclaimer is it still in force. Rava explains that the Mishnah is speaking about a person who recalls having made a disclaimer, but does not remember the details (e.g., he made the stipulation about certain items and does not recall which ones). In this case, if he references the stipulation when making his neder, saying, על דעת הראשונה אני נודר- “I am acting in accordance with my original intent,” then his stipulation is valid and the neder is ineffective. If he did not, then he has uprooted his original stipulation.