A case of uncertain naziriteship TB Nazir 8

Just like all other vows with conditions, a person's mindset determines whether the vow of nezirut takes effect or not. On today's daf TB Nazir 8 Rabbi Shimon and Rabbi Yehuda argue over this point “as it is taught in a baraita: With regard to one who says: I am hereby a nazirite on the condition that this pile of grain will be found to contain at least one hundred kor, and he went to measure the pile and found that it was stolen or lost, making it impossible to determine whether it contained one hundred kor, Rabbi Shimon prohibits him to drink wine or cut his hair, as he holds that in a case of uncertain naziriteship one is required to act stringently. Similarly, in the case in the mishna, since it is not known whether one intended to accept naziriteship according to the number of mustard seeds in the basket or according to the number of gourds there, he must act stringently..

“Conversely, Rabbi Yehuda permits him to drink wine or cut his hair, as he holds that in a case of uncertain naziriteship one is permitted to act leniently. The naziriteship does not take effect, since the pile might have contained less than one hundred kor.” (Sefaria.org translation)

Rabbi Shimon holds that the person's mindset was always to become a nazir. So even when there is a doubt whether his pile of grain contained 100 kors or not we decide stringently and say this person who made the condition becomes a nazir. Rabbi Yehuda holds that the person never had a mind to become a nazir unless his pile of grain contained 100 kors. When there's a doubt whether the condition has been met, we decide leniently and say that this person doesn't become a nazir.

Rambam poskins like Rabbi Yehuda that "in a case of uncertain naziriteship one is permitted to act leniently." (Mishneh Torah, the Book of Vows, the Laws of Nazir, chapter 2 halakha 9) Usually in a doubtful case of a Torah law, we decide Jewish law stringently; however, I think that Jewish law was decided leniently even though the concept of a nazir is in Torah origin because the rabbis did not approve of people becoming nezirim.