Leviticus 18:3-7

After the doings of the land of Egypt, wherein ye dwelt, shall ye not do: and after the doings of the land of Canaan, whither I bring you, shall ye not do: neither shall ye walk in their ordinances.

Ye shall do my judgments, and keep mine ordinances, to walk therein: I am the LORD your God.

Ye shall therefore keep my statutes, and my judgments: which if a man do, he shall live in them: I am the LORD.

None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD.

The nakedness of thy father, or the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness.