201 Abraham moved south to the Negev and lived for a while between Kadesh and Shur, and then he moved on to Gerar. While living there as a foreigner, 2 Abraham introduced his wife, Sarah, by saying, "She is my sister." So King Abimelech of Gerar sent for Sarah and had her brought to him at his palace.
3 But that night God came to Abimelech in a dream and told him, "You are a dead man, for that woman you have taken is already married!" 4 But Abimelech had not slept with her yet, so he said, "Lord, will you destroy an innocent nation? 5 Didn't Abraham tell me, 'She is my sister'? And she herself said, 'Yes, he is my brother.' I acted in complete innocence! My hands are clean." 6 In the dream God responded, "Yes, I know you are innocent. That's why I kept you from sinning against me, and why I did not let you touch her. 7 Now return the woman to her husband, and he will pray for you, for he is a prophet. Then you will live. But if you don't return her to him, you can be sure that you and all your people will die."
8 Abimelech got up early the next morning and quickly called all his servants together. When he told them what had happened, his men were terrified. 9 Then Abimelech called for Abraham. "What have you done to us?" he demanded. "What crime have I committed that deserves treatment like this, making me and my kingdom guilty of this great sin? No one should ever do what you have done! 10 Whatever possessed you to do such a thing?" 11 Abraham replied, "I thought, 'This is a godless place. They will want my wife and will kill me to get her.' 12 And she really is my sister, for we both have the same father, but different mothers. And I married her.
Matthew Henry's Commentary on Genesis 20:1-12
Commentary on Genesis 20:1-8
(Read Genesis 20:1-8)
Crooked policy will not prosper: it brings ourselves and others into danger. God gives Abimelech notice of his danger of sin, and his danger of death for his sin. Every wilful sinner is a dead man, but Abimelech pleads ignorance. If our consciences witness, that, however we may have been cheated into a snare, we have not knowingly sinned against God, it will be our rejoicing in the day of evil. It is matter of comfort to those who are honest, that God knows their honesty, and will acknowledge it. It is a great mercy to be hindered from committing sin; of this God must have the glory. But if we have ignorantly done wrong, that will not excuse us, if we knowingly persist in it. He that does wrong, whoever he is, prince or peasant, shall certainly receive for the wrong which he has done, unless he repent, and, if possible, make restitution.
Commentary on Genesis 20:9-13
(Read Genesis 20:9-13)
See here much to blame, even in the father of the faithful. Mark his distrust of God, his undue care about life, his intent to deceive. He also threw temptation in the way of others, caused affliction to them, exposed himself and Sarah to just rebukes, and yet attempted an excuse. These things are written for our warning, not for us to imitate. Even Abraham hath not whereof to glory. He cannot be justified by his works, but must be indebted for justification, to that righteousness which is upon all and unto all them that believe. We must not condemn all as hypocrites who fall into sin, if they do not continue in it. But let the unhumbled and impenitent take heed that they do not sin on, thinking that grace may abound. Abimelech, being warned of God, takes the warning; and being truly afraid of sin and its consequences, he rose early to pursue the directions given him.