Commentary for Sanhedrin 49:10
ההוא טבחא דאישתכח דנפקא טריפתא מתותי ידיה פסליה רב נחמן ועבריה אזל רבי מזיה וטופריה סבר רב נחמן לאכשוריה
must be free fromdoubt.<span class="x" onmousemove="('comment',' Lit., 'applies only to distinct utterance.' This refers to the following: A and B were sitting by the road-side, and a man passed them. Whereupon A said to B: If the man who has passed is a Nazir, as I maintain he is, then I too will take the vow of neziruth; and B said that he for his part would take the vow if he were not. R. Tarfon ruled that the vow is not binding even upon him whose view was subsequently found to be correct, for the vow was based on a doubtful matter, whereas neziruth requires a distinct and explicit pledge. (V. Nazir 34a). R. Judah himself may thus, notwithstanding his statement in the Mishnah, which is only explanatory of the view of the Rabbis, concur in R. Tarfon's view. With respect to the actual reasoning of the Talmud, Rashi states: This proves that in R. Tarfon's opinion, an undertaking dependent on an unknown circumstance is not binding, and therefore the same applies to gambling, each gambler undertaking to pay his opponents without knowing the latter's strength, and therefore the gambler is akin to a robber, as explained on p. 143, n. 2, whether gambling, is his sole occupation or not. ');"><sup>10</sup></span>