Leviticus 18:6-7

Laws of Sexual Relations

18:6 “‘No man is to approach any close relative to have sexual intercourse with her. I am the Lord. 18:7 You must not expose your father’s nakedness by having sexual intercourse with your mother. She is your mother; you must not have intercourse with her.

Mark 12:19

12:19 “Teacher, Moses wrote for us: ‘If a man’s brother dies and leaves a wife but no children, that man must marry the widow and father children for his brother.’