Sanhedrin 75B

אמר אביי: הכי קאמר, מנין לעשות שאר הבא ממנו כשאר הבא ממנה? נאמר כאן ״זמה״ ונאמר להלן ״זמה״ וכו׳. והא בשאר דידיה לא כתיבא ביה ״זמה״!

Abaye says: This is what the baraita is saying. From where is it derived to render a relative who comes from his family, e.g., the daughter of his daughter and the daughter of his son, like a relative who comes from her family, e.g., the daughter of his wife and the daughter of his wife’s daughter? Lewdness is stated here and lewdness is stated there. Just as there, the Torah renders the status of male relatives like that of female relatives, so too here, the Torah renders the status of males like that of females. The Talmud asks: But isn’t it so that with regard to a relative from his family the term lewdness is not written, as the verse states: “The nakedness of your son’s daughter, or of your daughter’s daughter, their nakedness you should not expose; for theirs is your own nakedness” (Leviticus 18:10)?

אמר רבא: אמר לי רב יצחק בר אבודימי, אתיא ״הנה״ ״הנה״, אתיא ״זמה״ ״זמה״.

Rava says: Rav Yitzḥak bar Avudimi said to me: The equation of his relative to her relative is derived by means of a verbal analogy between the word “henna” written with regard to his relative: “The nakedness of your son’s daughter, or of your daughter’s daughter, their nakedness you should not expose; for theirs [henna] is your own nakedness” (Leviticus 18:10), and the word “henna” written with regard to her relative: “You should not uncover the nakedness of a woman and her daughter; you should not take her son’s daughter, or her daughter’s daughter, to uncover her nakedness; they [henna] are near kinswomen; it is lewdness” (Leviticus 18:17). Additionally, it is derived from a verbal analogy between the word “lewdness” (Leviticus 18:17) and the word “lewdness” in the verse: “And if a man takes a woman and her mother, it is lewdness; they should be burned with fire both him and them, and there should be no lewdness among you” (Leviticus 20:14).