Leviticus 20:17

20:17 “‘If a man has sexual intercourse with his sister, whether the daughter of his father or his mother, so that he sees her nakedness and she sees his nakedness, it is a disgrace. They must be cut off in the sight of the children of their people. He has exposed his sister’s nakedness; he will bear his punishment for iniquity.

Leviticus 22:13

22:13 but if a priest’s daughter is a widow or divorced, and she has no children so that she returns to live in her father’s house as in her youth, she may eat from her father’s food, but no lay person may eat it.