Leviticus 18:17
You must not have sexual intercourse with both a woman and her daughter; you must not take as wife either her son's daughter or her daughter's daughter to have intercourse with them. They are closely related to her -- it is lewdness.
Leviticus 20:14
If a man has sexual intercourse with both a woman and her mother, it is lewdness. Both he and they must be burned to death, so there is no lewdness in your midst.
Deuteronomy 27:23
Cursed is the one who has sexual relations with his mother-in-law.' Then all the people will say, 'Amen!'
Amos 2:7
They trample on the dirt-covered heads of the poor; they push the destitute away. A man and his father go to the same girl; in this way they show disrespect for my moral purity.