Kiddushin 36A

אחת היא.

are one prohibition.

אביי אמר: היינו טעמא דאיסי, דגמר ״קרחה״ ״קרחה״ מבני אהרן, מה להלן נשים פטורות ⁠– אף כאן נשים פטורות.

Abaye said that this is the reason of Isi for exempting women from the prohibition against baldness: As he learns the prohibition against causing baldness in grief over someone who is dead through a verbal analogy from the prohibition against causing baldness stated with regard to the sons of Aaron. The verse states with regard to priests: “They should not make baldness upon their head” (Leviticus 21:5). Just as there, with regard to priests, women are exempt, as the expression “the sons of Aaron” serves to exclude the daughters of Aaron, so too here, women are exempt.

ואי סבירא לן דכי כתיב קרא, בכולי עניינא הוא דכתיב, נשתוק קרא מיניה ותיתי בקל וחומר, ואנא אמינא: ומה כהנים שריבה בהם הכתוב מצות יתירות ⁠– ״בני אהרן״⁠ – ולא בנות אהרן, ישראל לא כל שכן?

The Talmud asks: But if we maintain that when God writes: “The sons of Aaron” (Leviticus 21:1), it is written with regard to the entire matter of that chapter, including the prohibition against causing baldness, let the verse be silent about this prohibition concerning all Jews. And this halakha could be derived through an a fortiori inference, as I could say the following: If in the case of priests, for whom the verse includes additional mitzvot, the prohibition against causing baldness applies only to the sons of Aaron and not the daughters of Aaron, is it not all the more so the case with regard to Israelites, who have fewer mitzvot, that only the men should be obligated and not the women?

אי לאו גזרה שוה הוה אמינא: הפסיק הענין.

The Talmud answers: Nevertheless, the verbal analogy is necessary. As, were it not for the verbal analogy I would say that the halakhot of ritual impurity concluded discussion of that matter, and the prohibition against causing baldness applies to all the descendants of Aaron, including women.