MISHNA: Which offspring of forbidden relations have the status of a mamzer? It is the offspring of a union with any next of kin that is subject to a Torah prohibition that he should not engage in sexual relations with them; this is the statement of Rabbi Akiva. Shimon HaTimni says: It is the offspring of a union with any forbidden relation for which one is liable to receive karet at the hand of Heaven. And the halakha is in accordance with his statement. Rabbi Yehoshua says: It is the offspring of a union with any forbidden relation for which one is liable to receive court-imposed capital punishment.

Rabbi Shimon ben Azzai said: I found a scroll recording people’s lineages in Jerusalem, and it was written in it that so-and-so is a mamzer from an adulterous union with a married woman, a sin punishable by court-imposed capital punishment. The only reason for the scroll to state the reason that this individual is a mamzer is in order to support the statement of Rabbi Yehoshua.

The mishna delineates the circumstances in which it is prohibited to engage in relations with the sister of one’s wife and the sister of one’s yevama: If a man’s wife died, he is permitted to her sister. If he divorced her and then she died, he is permitted to her sister. If he divorced his wife and then she was married to another and then died, he is permitted to her sister. If his yevama died, he is permitted to her sister. If he performed ḥalitza with her and then she died, he is permitted to her sister. If after ḥalitza she was married to another and then died, he is permitted to her sister. The principle underlying all these cases is that the prohibition against engaging in relations with her sister only applies while the wife or yevama remain alive, irrespective of their current relationship to the man.

GEMARA: What is Rabbi Akiva’s reasoning? As it is written: “A man shall not take his father’s wife, and he shall not uncover his father’s cloak” (Deuteronomy 23:1). This teaches that a cloak that his father saw, i.e., a woman with whom his father engaged in sexual relations, the son may not uncover.

And in this interpretation of the verse, Rabbi Akiva holds in accordance with the opinion of Rabbi Yehuda, who said: The verse states only that such relations are forbidden, but they would not render him liable to receive karet; perforce the verse speaks of a woman raped by one’s father, since she is one of the women with whom relations render one liable for violating a prohibition. The verse could not refer to one’s father’s wife since relations with her render one liable to receive karet.

The Gemara completes its explanation of Rabbi Akiva’s opinion: And in close proximity to that verse is the verse: “A mamzer shall not enter into the congregation of the Lord” (Deuteronomy 23:3). Apparently, even from these forbidden relations, which render one liable for the violation of a prohibition, the offspring is a mamzer.

The Gemara asks: But according to Rabbi Simai, who holds that Rabbi Akiva includes as a mamzer the offspring of all other forbidden relations for which one is liable for violation of a prohibition, even those that are not with his next of kin; and also according to Rabbi Yeshevav, who holds that Rabbi Akiva includes even the offspring of relations for which one is liable for the violation of a positive mitzva; since according to them, Rabbi Akiva includes cases that are not similar to the case of a woman raped by his father, what is his source?

The Gemara answers: They derive it from the verse that states: “And he shall not uncover his father’s cloak” (Deuteronomy 23:1). The word “and” is superfluous and serves to include additional cases.

And Shimon HaTimni holds in accordance with the opinion of the Rabbis, who say: It is with regard to the widow waiting for his father to perform levirate marriage that the verse is speaking, and it indicates that she is one of the women with whom relations render one liable to receive karet. And in close proximity to that verse is the verse: “A mamzer shall not enter into the congregation of the Lord” (Deuteronomy 23:3). Apparently, only the offspring of a union for which one is liable to receive karet is a mamzer.

And how does Rabbi Yehoshua derive his opinion? If the verses should be derived as Rabbi Akiva and Shimon HaTimni suggest, let the Merciful One write only: “He shall not uncover his father’s cloak.” It is unnecessary for the verse to mention the prohibition with regard to one’s father’s wife, as the fact that the offspring of that union is a mamzer would be known through an a fortiori inference, since that prohibition is more stringent than the one derived from the verse: “And shall not uncover his father’s cloak.” Why do I need both the clause “a man shall not take his father’s wife” and the clause “and shall not uncover his father’s cloak”? Rather, is it not that this is what the Torah is saying: Only the offspring of relations with the woman mentioned in the verse after the words “a man shall not take” until the words “he shall not uncover,” i.e., his father’s wife, is a mamzer, but the offspring of relations with the woman mentioned beyond that point, i.e., the woman referred to as “his father’s cloak,” is not a mamzer.

§ Abaye said: All tanna’im in the mishna agree with regard to one who engages in sexual relations with a menstruating woman,