The Gemara challenges this conclusion: All of the exemptions from levirate marriage for forbidden relatives listed in the mishna are also derived from a homiletical interpretation. The Gemara responds: Although the matter of levirate marriage is derived from a homiletical interpretation, the main aspect of their prohibition is explicitly written. By contrast, with regard to his daughter from a woman he raped but did not marry, the main aspect of this prohibition is derived by homiletical interpretation, as the prohibition itself is not written explicitly in the Torah.

As Rava said: Rav Yitzḥak bar Avdimi said to me: This prohibition is derived by means of a verbal analogy between the word hena, in the verse: “The nakedness of your son’s daughter, or of your daughter’s daughter, even their nakedness you shall not uncover; for theirs [hena] is your own nakedness” (Leviticus 18:10) and the word hena in a different verse: “You shall not uncover the nakedness of a woman and her daughter; you shall not take her son’s daughter, or her daughter’s daughter, to uncover her nakedness: they [hena] are near kinswomen; it is wickedness” (Leviticus 18:17), indicating that every daughter is prohibited, even one from rape, just like one’s daughter through his wife.

Furthermore, it is derived from a verbal analogy between the word “wickedness” (Leviticus 18:17) and the word “wickedness” in the verse: “And if a man take with his wife also her mother, it is wickedness; they shall be burnt with fire, both he and they, that there be no wickedness among you” (Leviticus 20:14), that one who has sexual intercourse with a daughter from a rape is liable to burning.

§ The Gemara asks: Now that you said that all matters that are derived from a homiletical interpretation are dear to the tanna, and therefore he gives them precedence, let him teach the case of a wife’s sister last, as this is the source of the halakha and is therefore the most straightforward case. The Gemara responds: Since the tanna was dealing with the prohibition with regard to different types of sisters, he also taught together with them the prohibition with regard to his wife’s sister.

The Gemara asks: But if so, let him teach this entire section involving sisters at the end, when he mentions a wife’s sister. Rather, the Gemara rejects the above answer in favor of an alternative explanation: The tanna cited the cases in order of closeness, i.e., the mishna is ordered in accordance with the relative closeness of the various incestuous relations. How so? The tanna taught the cases of one’s daughter, and the daughter of his daughter, and the daughter of his son, who are his own blood relatives.

And since he taught three generations of one’s offspring below, i.e., his daughter, his daughter’s daughter, and his son’s daughter, he also taught three generations of his wife’s offspring below, i.e., his wife herself, her daughter, and her daughter’s daughter. And since he taught three generations of his wife’s offspring below, he also taught three generations of her family above, i.e., from previous generations, namely herself, her mother, i.e., his mother-in-law, and his mother-in-law’s mother.

And afterward he taught the case of his sister and his mother’s sister, who are his own blood relatives but less closely related to him than his daughter. And since he was dealing with the prohibition with regard to sisters, he also taught the case of his wife’s sister. And by right the tanna should have preceded the case of his daughter-in-law before that of a wife of a brother with whom he did not coexist, as it is not due to their relationship that she is prohibited but rather because she is excluded from the mitzva of levirate marriage. However, since he was dealing with the prohibition with regard to siblings, he taught the case of a wife of a brother with whom he did not coexist, as this also involves a sibling. And then the tanna taught the case of his daughter-in-law.

§ The Gemara continues to analyze the language of the mishna: And why does the tanna specifically teach: They exempt their rival wives? Let him teach: They prohibit them, as ultimately the rival wives are not only exempt from levirate marriage but each is actually forbidden to her yavam. The Gemara explains that if he had taught: They prohibit them, I would say that this means it is prohibited to enter into levirate marriage, but she must perform ḥalitza. Therefore, it teaches us using the language of exemption to indicate that she is entirely exempt and does not even perform ḥalitza.

The Gemara raises a difficulty: If so, let him teach: She is prohibited from performing ḥalitza. The Gemara rejects this suggestion: It is impossible to formulate the halakha in this manner, as even if they perform ḥalitza, what has he really done? What is wrong with a man allowing a woman to take off his shoe, which is the act of ḥalitza? Consequently, it is not possible to state: Prohibited from performing ḥalitza. The Gemara asks: Why not? There is in fact a prohibited element here: If you say she performs ḥalitza, it might be said that she may also enter into levirate marriage and that in this specific instance he performed ḥalitza merely because he did not wish to marry her. In that case, it might erroneously be claimed that if another wished to marry the rival wife of his yevama he is permitted to enter into levirate marriage.

In light of the previous argument, the Gemara suggests another reason that the mishna does not use the expression: Prohibited. Since it is only in cases where the mitzva of levirate marriage applies that the rival wife is forbidden to him, and where no mitzva applies she is permitted, as it is permitted for the man to marry the widowed rival wife of a non-relative, due to that reason he taught: They exempt their rival wives, and not: They prohibit them. In other words, the tanna is teaching that they are not prohibited to him in their own right.

§ The Gemara continues its analysis of the wording of the mishna. And why does the tanna specifically teach: Exempt from ḥalitza and from levirate marriage? Let him teach: Exempt from levirate marriage, alone. The Gemara answers: If he were to teach: From levirate marriage, I would say that she must perform ḥalitza and she must not enter into levirate marriage. The tanna therefore teaches us that every woman who is eligible for levirate marriage is eligible for ḥalitza, and anyone who is ineligible for levirate marriage is likewise ineligible for ḥalitza, as no obligation of ḥalitza applies unless there is an obligation of a levirate marriage.

§ The Gemara further inquires: And let him teach: From levirate marriage and from ḥalitza, as the Torah states the option of levirate marriage first. Alternatively, let him teach: From ḥalitza, alone, as this would indicate that she may not enter into levirate marriage either. The Gemara answers: This mishna is in accordance with the opinion of Abba Shaul, who said: The mitzva of ḥalitza takes precedence over the mitzva of levirate marriage, as he maintains that one who does not enter into levirate marriage for the sake of Heaven transgresses the prohibition against marrying one’s brother’s wife, and therefore it would be better in every case to perform ḥalitza. Consequently, the tanna mentions ḥalitza before levirate marriage.

§ The Gemara asks another question with regard to the language of the mishna: The enumeration of the first clause of the mishna: Fifteen women, which indicates that those women alone are included in this list, serves to exclude what? Which other cases might have been included? And the enumeration of the latter clause, which states: These exempt their rival wives, again meaning these and no others, serves to exclude what? Since the mishna specifies only these women and no others, the Gemara asks which other women might have been included in these lists.