Nedarim

MISHNAH. [IF ONE VOWS,] 'KONAM, IF I TASTE WINE TO-DAY, HE IS FORBIDDEN ONLY UNTIL IT GETS DARK; [IF HE SAYS] 'THIS SABBATH,'  HE IS FORBIDDEN THE WHOLE WEEK AND THE SABBATH BELONGS TO THE PAST;  'THIS MONTH,' HE IS FORBIDDEN THE WHOLE OF THAT MONTH, BUT THE BEGINNING OF THE [FOLLOWING] MONTH BELONGS TO THE FUTURE;  'THIS YEAR,' HE IS FORBIDDEN THE WHOLE YEAR, WHILST THE BEGINNING OF THE [FOLLOWING] YEAR BELONGS TO THE FUTURE; THIS SEPTENNATE,'  HE IS FORBIDDEN THE WHOLE OF THAT SEPTENNATE, AND THE [FOLLOWING] SABBATICAL YEAR BELONGS TO THE PAST.  BUT IF HE SAYS, 'ONE DAY,' 'ONE SABBATH,' 'ONE MONTH,' 'ONE YEAR,' [OR] 'ONE SEPTENNATE,' HE IS FORBIDDEN FROM DAY TO DAY.  [IF ONE VOWS,] 'UNTIL PASSOVER, HE IS FORBIDDEN UNTIL IT ARRIVES; 'UNTIL IT BE' [PASSOVER], HE IS FORBIDDEN UNTIL IT GOES;  'UNTIL PENE  PASSOVER,' R. MEIR SAID: HE IS FORBIDDEN UNTIL IT ARRIVES; R. JOSE SAID: UNTIL IT GOES. GEMARA. 'KONAM, IF I TASTE WINE' etc. R. Jeremiah  said: At nightfall he must obtain absolution iron, a Sage.  What is the reason? — R. Joseph said: 'To-day' is forbidden as a precautionary measure on account of 'one day'