Nedarim

MISHNAH. VOWS IN ERROR: [IF ONE SAYS, 'KONAM,] IF I ATE OR DRANK, AND THEN REMEMBERED THAT HE HAD; OR, 'IF I EAT OR DRINK,' AND THEN FORGOT [HIS VOW] AND ATE OR DRANK; [OR] 'KONAM BE ANY BENEFIT WHICH MY WIFE HAS OF ME, BECAUSE SHE STOLE MY PURSE OR BEAT MY CHILD, AND IT WAS SUBSEQUENTLY LEARNT THAT SHE HAD NOT BEATEN HIM NOR STOLEN; ALL THESE ARE VOWS IN ERROR. IF A MAN SAW PEOPLE EATING [HIS] FIGS AND SAID TO THEM, LET THE FIGS BE A KORBAN TO YOU,' AND THEN DISCOVERED THEM TO BE HIS FATHER OR HIS BROTHERS,  WHILE OTHERS WERE WITH THEM TOO — BETH SHAMMAI MAINTAIN: HIS FATHER AND BROTHERS ARE PERMITTED, BUT THE REST ARE FORBIDDEN. BETH HILLEL RULE: ALL ARE PERMITTED. GEMARA. It was taught: Just as vows in error are permitted, so are oaths in error.  What are oaths in error? — E.g., those of R. Kahana and R. Assi. One said, I swear that Rab taught this, whilst the other asserted, I swear that he taught this: thus each swore truthfully according to his belief. IF A MAN SAW PEOPLE EATING [HIS] FIGS. We learnt elsewhere: The Sabbaths and festivals are suggested as an opening [for regret].  Before then the ruling was that for those day's the vow is canceled, but for others it is binding; until R. Akiba taught: A vow which is partially annulled is entirely annulled. Rabbah said: All agree that if he said, 'Had I known that my father was among you I would have declared, "You are all forbidden except my father",' all are forbidden but his father is permitted. They differ only if he asserted, 'Had I known that my father was among you. I would have said, "So-and-so are forbidden and my father is permitted".'