Leviticus 13:5

13:5 The priest must then examine it on the seventh day, and if, as far as he can see, the infection has stayed the same and has not spread on the skin, then the priest is to quarantine the person for another seven days.

Leviticus 18:9

18:9 You must not have sexual intercourse with your sister, whether she is your father’s daughter or your mother’s daughter, whether she is born in the same household or born outside it; you must not have sexual intercourse with either of them.