Nazir 34A

אילימא רבי טרפון ⁠— מי הוי נזיר? כיון דבשעתא דקא נזר לא ידע אי פלוני הוא ואי לא, מי חלה עליה נזירות? והתניא, רבי יהודה אומר משום רבי טרפון: אין אחד מהן נזיר, לפי שלא נתנה נזירות אלא להפלאה!

If we say it is the opinion of R' Tarfon, even in a case where the individual in question came before us and identified himself, is the one who claimed to know his identity a nazirite? Since at the time when he vowed he did not know whether the subject of their debate is so-and-so or not, does naziriteship take effect with regard to him? But isn’t it taught in a baraita (Tosefta 3:19) that R' Yehuda says in the name of R' Tarfon: In the case of the Mishnah not one of the 6 people is a nazirite, since naziriteship is imposed upon someone only if the vow is stated with explicitness [hafla’a]. The Torah says that a vow must be “clearly” pronounced, as the verse states: “When either man or woman should clearly utter [yafli] a vow, the vow of a nazirite” (Numbers 6:2). This verse indicates that his vow is valid only if it is explicit.

אלא רבי יהודה דכרי הוא. דתניא: ״הריני נזיר על מנת שיהא בכרי הזה מאה כור״, והלך ומצאו שנגנב או שאבד ⁠— רבי שמעון אוסר, ורבי יהודה מתיר.

Rather, the Mishnah represents the opinion of R' Yehuda, as stated with regard to a heap of grain. As it is taught in a baraita (Tosefta 2:9): If someone said: I am hereby a nazirite on the condition that this heap of grain contains 100 kor, a measurement of volume, and when he went to measure it he discovered that the heap was stolen or lost, so that the amount it held cannot be determined, R' Shimon deems him prohibited in all the halakhot of naziriteship, as the heap might have contained 100 kor. And R' Yehuda deems him permitted, as he maintains that the halakha is lenient in cases of uncertain naziriteship. R' Yehuda’s reasoning applies equally to the case of the Mishnah.