On his blog, DeepStrength commented:
Abraham’s intent was to protect Sarah. It appears that God honored that rather than bring down Abraham for his sin there.
I saw this idea put forward in a thread at Dalrock’s too, but it is not supported by Scripture.
10 Now there was a famine in the land. So Abram went down to Egypt to sojourn there, for the famine was severe in the land. 11 When he was about to enter Egypt, he said to Sarai his wife, “I know that you are a woman beautiful in appearance, 12 and when the Egyptians see you, they will say, ‘This is his wife.’ Then they will kill me, but they will let you live. 13 Say you are my sister, that it may go well with me because of you, and that my life may be spared for your sake.” 14 When Abram entered Egypt, the Egyptians saw that the woman was very beautiful. 15 And when the princes of Pharaoh saw her, they praised her to Pharaoh. And the woman was taken into Pharaoh’s house. 16 And for her sake he dealt well with Abram; and he had sheep, oxen, male donkeys, male servants, female servants, female donkeys, and camels.
And with Abimelech:
10 And Abimelech said to Abraham, “What did you see, that you did this thing?” 11 Abraham said, “I did it because I thought, ‘There is no fear of God at all in this place, and they will kill me because of my wife.’ 12 Besides, she is indeed my sister, the daughter of my father though not the daughter of my mother, and she became my wife. 13 And when God caused me to wander from my father’s house, I said to her, ‘This is the kindness you must do me: at every place to which we come, say of me, “He is my brother.”’”
Abraham’s thought was explicitly to protect himself. There is no mention or inference that he withheld the truth for Sarah’s sake. In fact, Abraham himself says it was a kind of trade: he gives Sarah kindness with marriage (provision, etc.) and she gives him the “kindness” of refusing to confess he is her husband. It’s probably too far to say that Abraham whored Sarah out, but he does go that direction.
Abraham, as a husband, is a kind of evil master who removes his protection from his prized servant when such protection is most needed! But because Sarah submitted to God by submitting to her husband, it is God who protects her in the houses of Pharaoh and Abimelech. It is not for the sake of Abraham’s righteousness, but because of Sarah’s, and Pharoah’s, and Abimelch’s, and because of God’s own righteousness. The only person who is presented as unrighteous is, in fact, Abraham; who (predictably) falsely projects his own unrighteousness (regarding Sarah) onto others. Understanding this is important when considering the elevation of Sarah in 1 Peter 3. It is a reiteration by example of Peter’s instruction that wives submit to unbelieving husbands just as Sarah submitting to her literally unfaithful husband and yet trusted in the Lord.
By withholding the truth, Abraham trangressed the (as yet ungiven) Ninth Commandment. He bore false witness against his neighbor–which threatened them with death!–upon whose land he was living and from whom Abraham profited.
Abraham is a rare scoundrel. The beginning of Chapter 12 God called Abram to Canaan and promising him to become a great nation. Abrams strikes out for Canaan, finds a famine, and so heads into Egypt. Five minutes after God’s promise, Abram is bearing false witness against Pharaoh, Pharaoh’s men, and Sarah. Years later in chapter 17 God again comes to Abram and again promises that he will father a nation. A year later Isaac is born. In between there, Abraham offers his wife to Abimelech. To further confound us moderns he did these things without telling a lie. He is a legalist of the first order, and an obvious ancestor of the Pharisees.
There is no call for anyone to do unrighteousness because those near us are unrighteous or unworthy. God chose and used Abraham despite his unrighteousness, and Sarah demonstrated righteousness by her own hand despite Abraham’s unrighteousness; which means without rebelling. Do not be fooled into thinking that only those who appear righteous are in the Lord’s hands as His tools.
Which brings us to the supposed conundrum of whether lying to Nazis to save Jews or lying to pedophiles to protect children is good. The answer is not “Yes” or “No”, but “Grace” and “Forgiveness”. The man who lies to (but does not bear false witness against) murderers and perverts protects both the victims and the perpetrators. Lying is to be avoided just as kings must avoid having too many wives or horses, but lying is not the same as bearing false witness against your neighbor; which is being anything less than truthful with the intent to bring them down. So lying to your Nazi countrymen with the intent to lead them into a deathtrap is unrighteous all around. Falsely swearing there are no Jews in your attic is more righteous —by virtue of love–than surrendering them, and anyone who loves the truth, you, Jews, or Nazis (as Christ did) will be quick to see and forgive.