Leviticus 18:6
None of you shall approach to any who are near of kin to him, to uncover their nakedness. I am Jehovah.
Leviticus 18:7-19
You shall not uncover the nakedness of your father or the nakedness of your mother. She is your mother; you shall not uncover her nakedness.
Leviticus 20:11-12
And the man who lies with his father's wife has uncovered his father's nakedness. Both of them shall surely be put to death. Their blood shall be on them.
Leviticus 20:17-21
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 wicked thing. And they shall be cut off in the sight of their people. He has uncovered his sister's nakedness; he shall bear his iniquity.