The source of when a positive commandment takes precedence over a prohibition TB Nazir 41

Back on daf TB Nazir 40a we learned that three people are obligated to shave. “We learned in a mishna there (Nega’im 14:4): Three types of people must shave their hair, and their shaving is a mitzva: A nazirite; and a leper (I’m going to use the Hebrew term metzora because it is poorly translated as a leper. This unfortunate person does not have Hansen’s disease-gg), as it is stated: “And he who is to be cleansed shall wash his clothes, and shave off all his hair” (Leviticus 14:8–9). And the third category is Levites, when they were first sanctified for their service, as it is stated: “And this you shall do to them to cleanse them: Sprinkle the water of purification upon them, and let them cause a razor to pass over all their flesh” (Numbers 8:7). And with regard to all of them, if they shaved with an implement other than a razor, or if they left two hairs uncut, they have done nothing, i.e., they have not fulfilled their obligation.” (Sefaria.org translation)

Daf TB Nazir 41 analyzes how we know that a metzora must shave with a razor. With this analysis the Gemara provides the source of an important halakhic rule. According to the Mishna all three categories of these people must shave with a razor. We know that a nazir and a Levite must shave with the razor because verses in the Torah explicitly say so. However, the Torah never explicitly says that the nazir must shave with a razor. The Gemara provides two alternative explanations how we learn that a nazir must shave with a razor too. I am only going to share the first explanation because this is the source of an important halakhic principle.

“What is the reason of the Rabbis; how do they derive from this halakha that a leper must shave with a razor? As it is taught in a baraita that the verse states with regard to the shaving of a leper: “He shall shave all his hair off his head and his beard” (Leviticus 14:9). Since the verse states: “All his hair,” what is the meaning when the verse states: “His beard”? It is because it is stated with regard to priests: “Neither shall they shave off the corners of their beards” (Leviticus 21:5). One might have thought that the same should also apply to a leper, i.e. that a leper who was a priest should be prohibited from shaving his beard. For this reason the verse states: “His beard,” which emphasizes that despite the general prohibition barring a priest from shaving his beard, a priest who is a leper is obligated to do so.

“And from where do we derive that this shaving of a leper must be performed with a razor? It is as it is taught in a baraita, with regard to the prohibition against a priest shaving his beard in the verse “Neither shall they shave off the corners of their beards” (Leviticus 21:5): One might have thought that a priest should be liable even if he shaved his beard with scissors. The verse states, in the general prohibition issued to all Jewish men: “Neither shall you destroy the corners of your beard” (Leviticus 19:27). This teaches that one is liable only if he shaves in a destructive manner, by uprooting the hairs entirely, which excludes the use of scissors.

“One might have thought that even if he removed it with tweezers or planes he should be liable. The verse states: “Neither shall they shave off the corners of their beards” (Leviticus 21:5), which indicates that the priests are liable only for removing their beards in a manner of shaving. How so? What is the manner of shaving that involves destruction? You must say this is shaving with a razor. The Rabbis learn from here that the implement forbidden to a priest is the same one that must be used for the shaving of a leper, namely a razor.” (Sefaria.org translation)

A kohen, priest, who is a metzora faces a dilemma. On the one hand the Torah prohibits him from shaving his beard. On the other hand, the Torah says as a metzora he must as a mitzvah shave his beard. What is this poor kohen supposed to do? Reish Lakish provides us with the correct answer to this quandary.

“Any place where you find a positive mitzvah (מצְוָה עֲשֵׂה) and a prohibition (מצְוָה לֹא תַעֲשֶׂה) that clash with one another, if you can find some way to fulfill both, that is preferable; and if that is not possible, the positive mitzva will come and override the prohibition. In this case the leper can fulfill his duty with tweezers or a plane, and therefore it should be prohibited for him to shave with a razor. Since it was necessary for the verse to say that the positive mitzva for a leper to shave overrides the prohibition against destroying one’s beard, this proves that the mitzva can be performed only with a razor.” (Sefaria.org translation)

When there’s simultaneous tension between a positive mitzvah and prohibition and a person cannot fulfill both, the rule is that the positive mitzvah will take precedence over the prohibition! In our case the kohen who is a metzora observes the positive commandment and shaves with a razor and disregards the prohibition that kohanim are forbidden to shave their beards.