We have heard a similar story before with Abraham and Sarah. Keep in mind that Isaac has not been born yet. Ishmael is still in the camp and he is still Abraham’s only child at this point. They get to another kingdom, so remember that Abraham is not alone here. He is with his entire entourage, and he once again feels compelled to tell the residing king that Sarah is his sister. But we at least get an explanation as to why he does that. It doesn’t make matters any better, but at least we get an explanation. Look at vs. 13 and we find that from the time that Abraham and Sarah were together he had Sarah agree that whenever they traveled they would tell the ruler that she was his sister. So it didn’t just happen those two times that we read about in Genesis, it probably happened multiple times. Okay, that probably makes it much worse.
But we see that Abimelech had not touched Sarah, which is different from the other encounter that we had with Sarah and Pharaoh in chapter 12 of Genesis. But God had still closed the womb of everyone in King Abimelech’s house. But as a result of giving Sarah back to Abraham, God releases that closure and blesses Abraham and let’s Abimelech continue on in his reign. This comes as a result of Abraham praying to God on behalf of Abimelech’s life. Also, notice that God calls Abraham a prophet when he speaks to Abimelech. Not a title we normally ascribe to Abraham, but we find it here.