Nedarim 25B

מתני׳ נדרי שגגות ⁠— ״אם אכלתי ואם שתיתי״, ונזכר שאכל ושתה. ״שאני אוכל ושאני שותה״, ושכח ואכל ושתה. אמר: ״קונם אשתי נהנית לי שגנבה את כיסי, ושהכתה את בני״, ונודע שלא הכתו, ונודע שלא גנבה.

Mishnah: What are examples of vows that are unintentional that are dissolved, as taught at the beginning of the chapter? One who vows: This loaf is forbidden to me as if it were an offering [konam] if I ate or if I drank, and then he remembers that he ate or drank. Or, one who vows: This loaf is konam for me if I will eat or if I will drink, and he then forgets and eats or drinks. Also, one who said: Benefiting from me is konam for my wife because she stole my purse or she hit my son, and then it became known that she had not hit him or it became known that she had not stolen.

ראה אותן אוכלין תאנים, ואמר: ״הרי עליכם קרבן״, ונמצאו אביו ואחיו והיו עמהן אחרים. בית שמאי אומרים: הן מותרים, ומה שעמהם ⁠— אסורים. ובית הלל אומרים: אלו ואלו מותרין.

The Mishnah lists another example of an unintentional vow: One who saw people entering his courtyard and eating figs, and because he did not want them to do so he said: The figs are forbidden to you like an offering. And then it was found that his father and brother were in the group, and there were others with them as well, and certainly he did not intend to take a vow prohibiting his father and brother from eating the figs. In such a case, Beit Shammai says: They, his father and brother, are permitted to eat the figs, and those others that were with them are prohibited from doing so. And Beit Hillel says: Both these and those are permitted to eat the figs, as will be clarified in the Talmud.