Leviticus 20:17

And if a man shall take his sister, his father’s daughter, or his mother’s daughter, and see her nakedness, and she see his nakedness; it is a shameful thing; and they shall be cut off in the sight of the children of their people: he hath uncovered his sister’s nakedness; he shall bear his iniquity.

`And a man who taketh his sister, a daughter of his father or daughter of his mother, and he hath seen her nakedness, and she seeth his nakedness: it is a shame; and they have been cut off before the eyes of the sons of their people; the nakedness of his sister he hath uncovered; his iniquity he beareth.

And if a man takes his sister, daughter of his father or his mother, and has sex relations with her and she with him, it is an act of shame: they are to be cut off before the children of their people; he has had sex relations with his sister, and his sin will be on him.