ז מִי שֶׁאָמַר: קֹדֶם שֶׁקִּדַּשְׁתִּי אֶת אִשְׁתִּי קִדַּשְׁתִּי אֶת אֲחוֹתָהּ בִּפְנֵי פְּלוֹנִי וּפְלוֹנִי וְהָלְכוּ לָהֶם לִמְדִינַת הַיָּם, וְלֹא גֵּרַשְׁתִּיהָ וַהֲרֵי הִיא נְשׂוּאָה, אֵינוֹ נֶאֱמָן לְאָסְרָהּ עַל בַּעֲלָהּ, כָּל זְמַן שֶׁלֹּא יָבִיא עֵדִים. וַאֲפִלּוּ אִם תֹּאמַר הִיא: אֱמֶת שֶׁקִּדַּשְׁתַּנִי, אֵינָהּ נֶאֱמֶנֶת לֶאֱסֹר עַצְמָהּ עַל בַּעֲלָהּ. וַאֲפִלּוּ אִם יָבִיא עֵדִים שֶׁקִּדְּשָׁהּ. אִם נִתְקַדְּשָׁה אֲחוֹת אִשְׁתּוֹ בְּפָנָיו, אֵינָהּ נֶאֱסֶרֶת עַל בַּעֲלָהּ. וְזֶה אָסוּר בְּאִשְׁתּוֹ, שֶׁכֵּיוָן שֶׁאָמַר: שֶׁקִּדֵּשׁ אֲחוֹתָהּ תְּחִלָּה, נֶאֱסָר בִּקְרוֹבוֹת שְׁתֵּיהֶן. וְעַיֵּן לְעֵיל סוֹף סִימָן מ"ו:
7 Someone who says: Before I married my wife, I married her sister in front of "so and so," and they have since moved to another town, I never gave her a divorce, and she is now married. He is not believed to prohibit her from living with her husband, as long as witnesses are not brought (to prove otherwise). And even if she says: It is true that he married me, she is still not believed to prohibit herself from her husband, even if witnesses are brought that he married her. If his wife's sister was married in front of him, she is not prohibited from her husband, for this is prohibited with his wife, since it is says: he married her sister first, then he is prohibited from both family members.