Genesis 20:4 - Matthew Poole's English Annotations on the Holy Bible

Abimelech had not come near her, i.e. had not yet lain with her. A modest expression, like that of knowing a woman, Genesis 4:1, or going in to her, Genesis 6:4, or touching her, Proverbs 6:29 1 Corinthians 7:1, by which we are taught to use modesty in our speeches, and not, with the rude cynics, to express all things by their proper names. This clause and history was necessary to be added here for Sarah's vindication, and especially for the demonstration of Isaac's original from Abraham and Sarah, according to God's promise. Wilt thou slay also a righteous nation? i.e. innocent as to this matter. Compare 2 Samuel 4:11. He knew it was just and usual for God to punish a nation for their king's sins; and therefore, as became a good prince, he is solicitous, and prays for the safety of his nation: or else by nation he may mean his family, for some of them were not involved in the guilt of this fact.