New Defender's Study Bible Notes
12:12 they will kill me. A papyrus document from ancient Egypt does indeed tell of a pharaoh who had a beautiful woman brought to his court after murdering her husband, which would indicate that Abram’s concern was realistic.
12:13 my sister. Sarai was Abram’s half-sister (Genesis 20:12), so this was not an outright lie. Abram’s faith was still weak. He should have stayed in Canaan in spite of the famine. Having gone into Egypt, he should have been open and consistent in his testimony, and so should Sarai. Instead, they compromised, following human reason instead of God’s Word. God protected them in spite of it, but they lost their testimony with the Egyptians, whom they might otherwise have led back to God.