Lord, wilt thou slay also, &c.— Abimelech here deprecates the Divine wrath, and enters into a justification of his conduct; declaring that both Abraham and Sarah had united in attesting that Sarah was the sister of Abraham; and that he had not the least apprehension or design of committing so atrocious a crime, as that of taking away a man's wife, and defiling his bed; in the integrity of my heart, and the innocency of my hands, have I done this: a plea which the Almighty graciously admits, assuring Abimelech, that he knew this to be the case; yea, I know that thou didst this in the integrity of thy heart, without any knowledge of the connection, and consequently without any design to violate the marriage-bed: And (not for) I also withheld thee from sinning against me: therefore, &c. Observe hence, that immoral actions derive their chief turpitude from being offences against God: adultery is a sin against God; from which God withheld Abimelech, because of the integrity of his heart. It cannot however be reasonably inferred from this, that concubinage or polygamy is justifiable in the sight of God: but only that it was no crime in Abimelech; it was at most but a fault of ignorance, which is not inconsistent with integrity, since neither his own conscience condemned it, nor any law which he knew: so that he acted uprightly, in so far as he did nothing but what he judged lawful and right, according to the best of his knowledge.
Related Commentaries of Genesis 20:4
Genesis 20:4-5
4 But Abimelech had not come near her: and he said, Lord, wilt thou slay also a righteous nation?
5 Said he not unto me, She is my sister? and she, even she herself said, He is my brother: in the integrityb of my heart and innocency of my hands have I done this.