לֹא־יִקַּ֥ח אִ֖ישׁ אֶת־אֵ֣שֶׁת אָבִ֑יו וְלֹ֥א יְגַלֶּ֖ה כְּנַ֥ף אָבִֽיו׃ (ס)
Targum Jonathan on Deuteronomy
A man should not take a wife who is bowed down (or violated), or who hath had intercourse with his father, much less his father’s wife, nor disclose the skirt that covereth his father.