Leviticus 18:17

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

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.