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. 18 And if a man shall lie with a woman having her sickness, and shall uncover her nakedness; he hath made naked her fountain, and she hath uncovered the fountain of her blood: and both of them shall be cut off from among their people. 19 And thou shalt not uncover the nakedness of thy mother's sister, nor of thy father's sister; for he hath made naked his near kin: they shall bear their iniquity. 20 And if a man shall lie with his uncle's wife, he hath uncovered his uncle's nakedness: they shall bear their sin; they shall die childless. 21 And if a man shall take his brother's wife, it is impurity: he hath uncovered his brother's nakedness; they shall be childless.
Matthew Henry's Commentary on Leviticus 20:17-21
Commentary on Leviticus 20:10-27
(Read Leviticus 20:10-27)
These verses repeat what had been said before, but it was needful there should be line upon line. What praises we owe to God that he has taught the evil of sin, and the sure way of deliverance from it! May we have grace to adorn the doctrine of God our Saviour in all things; may we have no fellowship with unfruitful works of darkness, but reprove them.