Once again Abraham lied. Once again he told a foreign king his wife was his sister. And once again he was rebuked by a foreigner.
It seems to me, in His grace, God withholds the justice that was due to Abraham. He had already stumbled once in this same manner. Fearing once again that his life would be in danger, Abraham tells a half-truth for protection. This is the second time he has portrayed Sarah as his sister (ironically, his son Isaac would pass off his wife as his sister as well).
On top of this, Abraham sort of blames God for his problems instead of owning up to his lies.
So when God had me wander from my father’s house, I said to her: Show your loyalty to me wherever we go and say about me: ‘He’s my brother.’”
Genesis 20:13 HCSB
It’s like Abraham is saying, “Well, God made me wander, so of course I had to protect myself using this method.” Strangely, there doesn’t seem to be much pushback from God with these statements, which has left many commentators to either justify Abraham’s behavior or simply excuse it.
Personally, I think it speaks toward the grace of God. Even with a pagan king, it was God who supernaturally protected him from having relations with Sarah.
Then God said to him in the dream, “Yes, I know that you did this with a clear conscience. I have also kept you from sinning against Me. Therefore I have not let you touch her.
Genesis 20:6 HCSB
Consider the gravity of this statement. It was God who held back the enemy and the flesh so that the purity of the royal line of Christ could be preserved.
“Suppose Abimelech had taken Sarah and God had not intervened? Two seeds would have been at the door to Sarah’s womb, and to this day an element of doubt would cling to the ancestry of our Lord.”
Donald Barnhouse
It’s possible that the shame of being rebuked and corrected by a pagan king was enough of a consequence for Abraham. It was surely embarrassing as he was corrected previously by Pharoah from Egypt. Abraham’s response, however, goes to show how open his heart was to the correction of God. He prayed for Abimelech and God healed them. In the end, we can be confident Abraham learned his lesson and that all the glory went to the Lord.