Leviticus 18:6-8

American Standard Version

⁶ None of you shall approach to any that are near of kin to him, to uncover their nakedness: I am Jehovah. ⁷ The nakedness of thy father, even the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness. ⁸ The nakedness of thy father’s wife shalt thou not uncover; it is thy father’s nakedness.