Mishnayos Yevamos Perek 14 Mishnah 5

If two halakhically competent brothers were married to two sisters, one of whom is a deaf-mute and the other one halakhically competent, and the halakhically competent brother married to the deaf-mute sister died, what should the halakhically competent brother married to the halakhically competent sister do? The deaf-mute sister is released due to the prohibition with regard to a wife’s sister. If the halakhically competent brother married to the halakhically competent sister died, what should the halakhically competent brother married to the deaf-mute sister do? He divorces his wife with a bill of divorce, as the halakhically competent sister came before him for levirate marriage, and the status of her levirate bond is higher than the status of his marriage to his wife, a deaf-mute. And he releases his brother’s wife, who is not a deaf-mute, by means of ḥalitza, as they are both legally competent and can therefore perform ḥalitza.

שְׁנֵי אַחִים פִּקְחִים נְשׂוּאִים לִשְׁתֵּי אֲחָיוֹת, אַחַת חֵרֶשֶׁת וְאַחַת פִּקַּחַת, מֵת פִּקֵּחַ בַּעַל חֵרֶשֶׁת, מַה יַּעֲשֶׂה פִקֵּחַ בַּעַל פִּקַּחַת, תֵּצֵא מִשּׁוּם אֲחוֹת אִשָּׁה. מֵת פִּקֵּחַ בַּעַל פִּקַּחַת, מַה יַּעֲשֶׂה פִקֵּחַ בַּעַל הַחֵרֶשֶׁת, מוֹצִיא אֶת אִשְׁתּוֹ בְגֵט, וְאֶת אֵשֶׁת אָחִיו בַּחֲלִיצָה.