Nazir 58A

יכול אף מצורע כן ⁠— תלמוד לומר: ״ראשו״. ותניא אידך: ״ראשו״, מה תלמוד לומר? לפי שנאמר גבי נזיר ״תער לא יעבר על ראשו״, יכול אף נזיר מצורע כן ⁠— תלמוד לומר: ״ראשו״.

one might have thought that even a metzora should likewise be prohibited from rounding off his head. The verse therefore specifically states “his head” to teach that the mitzva for a metzora to remove all the hair of his head overrides the prohibition against rounding one’s head. And it was taught in another baraita: Why must the verse state: “His head,” with regard to a metzora? Since it states, with regard to a nazirite: “No razor should come upon his head” (Numbers 6:5), one might have thought that even a nazirite metzora should likewise be prohibited from shaving upon his purification. Therefore the verse states: “His head,” from which it is derived that a nazirite who contracted tzara'at must shave his head like any other metzora.

מאי לאו תנאי היא, למאן דאמר מנזיר, קסבר: הקפת כל הראש ⁠— לא שמה הקפה, וכי אתא קרא ⁠— למידחי את לא תעשה ועשה. ואידך סבר: הקפת כל הראש ⁠— שמה הקפה, וכי אתא קרא ⁠— למידחי לאו גרידא?

The Talmud explains: What, is it not correct to say that this is a dispute between tanna’im? According to the one who says that the additional term “his head” is to counter a possible prohibition derived from the case of a nazirite, he holds that rounding the entire head is not called rounding, and therefore there is no need for a verse to teach that a metzora can shave all the hair off his head. And when the verse “He should shave all his hair; his head” comes, it comes to override both the prohibition: “No razor should come upon his head,” and the positive mitzva stated with regard to a nazirite: “He should be sacred, he should let the locks of the hair of his head grow long” (Numbers 6:5). And the other tanna holds that rounding the entire head is called rounding, and consequently, when the verse comes, it serves to override only the prohibition against rounding one’s head.