Mishnayos Kiddushin Perek 2 Mishnah 7

אינן מקודשות – as it says in Scripture (Leviticus 18:18): “Do not marry a woman as a rival to her sister [and uncover her nakedness in the other’s lifetime].” At the time when they became rivals/associate wives to each other you have no legal marriage, even with one of them. And the same law applies to all the cases of consanguinity (i.e., where a man and woman are forbidden to each other) where they have [the punishment of] Divine extirpation, for the betrothal does not take effect.

ושלהן היתה – We understand from our Mishnah that a person who betroths with stolen goods, and even with her stolen goods is not betrothed. And we do not say that when he received it, it took effect, for since it is taught that “it was theirs and it was Seventh-year produce,” that because it was of the Seventh year and the produce was ownerless, because of that, the women are betrothed, but sisters cannot be betrothed [to one man], but if it (i.e., the produce) was not of the Seventh-year, for it was [in reality] theirs (i.e., belonging to the sisters), betrothal does not take effect with any one of them. But especially when one betroths with stolen [produce] prior to despair [of the original owner of getting it back], we say that it is not a betrothal, but when one betroths with stolen [produce] after [the original owner] despairs [of getting it back], his betrothal is a betrothal. And we understand also that one who betroths with Seventh-year produce is betrothed. And we don’t say that they are not his monies to take possession of them, but rather, since he took possession of them, it is his money for all matters. And we also understand that a woman can become an agent for her fellow [female], and even in a case where she becomes her rival. And even though that in all testimony where a woman is fit to, the rival is not fit for it. But her agency, however, since it was done, it was done. For here in these betrothals, they are made rivals one to the other when she accepts it, for it is taught that sisters cannot become betrothed [to the same man], but women who are strangers (i.e., not related) may be betrothed [together]. And our Mishnah is reconciled in the Gemara (Kiddushin 52a) according to this Halakha, that a person who betroths a woman and her daughter or [betroths] a woman and her sister, both (i.e., woman and daughter AND woman and her sister) are viewed as one, and they are not betrothed. For one was [regarding] a woman and her daughter and one was [regarding] a woman and her sister, such as the case where he said to both of them: “One of you is betrothed to me,” but he did not explicate to which of them he is betrothing, and one of them accepted the betrothal/Kiddushin on behalf of her [female] partner (i.e., either her sister or her daughter), or both of them accepted the Kiddushin/betrothal as one, betrothed, but both of them require a Jewish bill of divorce. And if he said: “[to the one] who is appropriate for me for engage in sexual relations is betrothed to me,” they are not betrothed, for each one of them (i.e., these pairs of women – woman and sister; woman and daughter) there is [the question] of doubting her [on account of] the sister and of his wife, and none of them are appropriate for sexual relations. And there is also the story (spelled out in our Mishnah) and among them, two are sisters and one [man] collected a basked containing chosen fruits and said to the one appropriate for sexual relations, “become betrothed to me.” But the Sages said, that sisters may not become betrothed [to one man], but strangers who were worthy for sexual relationships can be betrothed. But if one [man] said: “All of you are betrothed to me,” not a single one of them are betrothed to him, for just as sisters cannot become betrothed [together to the same man], so all the others cannot betrothed to him, since he said, “all of you.”