וְאִ֣ישׁ אֲשֶׁר־יִקַּ֣ח אֶת־אֲחֹת֡וֹ בַּת־אָבִ֣יו א֣וֹ בַת־אִ֠מּוֹ וְרָאָ֨ה אֶת־עֶרְוָתָ֜הּ וְהִֽיא־תִרְאֶ֤ה אֶת־עֶרְוָתוֹ֙ חֶ֣סֶד ה֔וּא וְנִ֨כְרְת֔וּ לְעֵינֵ֖י בְּנֵ֣י עַמָּ֑ם עֶרְוַ֧ת אֲחֹת֛וֹ גִּלָּ֖ה עֲוֺנ֥וֹ יִשָּֽׂא׃
A kto pojmie siostrę swoję, córkę ojca swego, albo córkę matki swojej, i ujrzy nagość jej i ona téż ujrzy nagość jego, - skażenie to; wytrąceni niechaj będą w oczach synów ludu swojego: nagość siostry swej odkrył, niechaj poniesie winę swą!
Jerusalem Talmud Sanhedrin
It is written, the genitals of a woman and her daughter you shall not uncover, and it is written, if a man take a woman and her mother, it is taboo. Everywhere is written lying with, but here is written taking, to teach you that he cannot be [criminally] liable for the second woman unless she be taken by him. Or maybe he is [criminally] liable only by marriage? We already said that there is no valid incestuous marriage. But is it not written: Nobody may marry his father’s wife, and he should not uncover his father’s garment’s corner? This comes to tell that she was permitted to him before his father married her. But is it not written: If a man take his brother’s wife? This comes to tell you that she was permitted to him before his brother married her. This is understood by levirate. But is it not written: You should not take a woman in addition to her sister? This comes to tell you that she was permitted to him before he married her sister. This is understood after her sister’s death. But is it not written: A man who would take his sister, his father’s daughter or his mother’s daughter, it is ḥesed? That you should not say that Cain married his sister, Abel married his sister, it is charitable, I was charitable with the first generations so the world could be inhabited; I said, the world was built on ḥesed. But is it not written: Widow, divorcee, and desecrated, these he shall not take? This comes to tell you that if he became betrothed to her, the betrothal is valid.