מִי שֶׁקִּדֵּשׁ אַחַת מִשְּׁתֵּי אֲחָיוֹת וְאֵין יָדוּעַ אֵי זֶה מֵהֶן קִדֵּשׁ וּמֵת וְלוֹ אָח. אֶחָד חוֹלֵץ לִשְׁתֵּיהֶן כְּדֵי לְהַתִּירָן לַאֲחֵרִים. הָיוּ לוֹ שְׁנֵי אַחִין אֶחָד חוֹלֵץ לְאַחַת מֵהֶן בַּתְּחִלָּה וְהַשֵּׁנִי מְיַבֵּם לַשְּׁנִיָּה עַל כָּל פָּנִים. אִם זוֹ הִיא שֶׁקִּדֵּשׁ אָחִיו הֲרֵי יִבֵּם אוֹתָהּ. וְאִם אֵינָהּ אֵשֶׁת אָחִיו הֲרֵי נָשָׂא אִשָּׁה מִשְּׁאָר הַנָּשִׁים וַאֲחוֹתָהּ שֶׁהָיְתָה אֵשֶׁת אָחִיו כְּבָר נֶחְלְצָה. אֲבָל לֹא יְיַבֵּם הָאַחַת תְּחִלָּה שֶׁמָּא הָאַחֶרֶת הִיא אֵשֶׁת אָחִיו וְנִמְצָא שֶׁנָּשָׂא קְרוֹבַת זְקוּקָתוֹ. קָדְמוּ שְׁנֵי הָאַחִים וְכָנְסוּ שְׁתֵּי הַיְבָמוֹת אֵין מוֹצִיאִין אוֹתָן מִיָּדָן:
[The following rules apply when a man] consecrates one of two sisters, but does not know which one he has consecrated and then dies [childless]. If he has one brother, [the brother] should perform chalitzah with both of them to enable them to marry other men. If he has two brothers, one of them should first perform chalitzah with one of [the sisters], and the other should perform yibbum with the other one [because of the following rationale]: If this was the woman consecrated by his brother, he performed yibbum with her. If she is not his brother's wife, he has married a woman [permitted to him] like any other woman, and chalitzah has already been performed for her sister, his brother's wife. One should not perform yibbum with one of the women first, for perhaps the other was in fact his brother's wife, and he will have married a relative of the woman who is obligated [to perform yibbum with] him. If, without asking Rabbinic advice, each of the brothers married one of the sisters, they are not forced to dissolve the marriage.
