17 "If a man marries his sister, the daughter of either his father or mother, and they have sex, that's a disgrace. They must be publicly cut off from their people. He has violated his sister and will be held responsible. 18 "If a man sleeps with a woman during her period and has sex with her, he has uncovered her 'fountain' and she has revealed her 'fountain' - both of them must be cut off from their people. 19 "Don't have sex with your aunt on either your mother's or father's side. That violates a close relative. Both of you are held responsible. 20 "If a man has sex with his aunt, he has dishonored his uncle. They will be held responsible and die childless. 21 "If a man marries his brother's wife, it's a defilement. He has shamed his brother. They will 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.