Genesis 20:10

And Abimelech said unto Abraham, What sawest thou, that thou hast done this thing?

The question is asked by Abimelech of Abraham during Abraham's sojourn among the Philistines, pressing him for what he had seen or what had led him to hide that Sarah was his wife by saying she was his sister. Abimelech knew the true God and had been directly instructed by God about taking Sarah, and he and his servants feared God over the matter. He restored Sarah to Abraham, and his people had a higher regard for morality than other nations of Palestine. Abraham's deception was prompted by unbelief and lack of trust in God's protection. Though his faith was real it was not yet perfect, showing that even the father of believers could fail to trust God at particular times.

Abimelech's stern questioning was a means God used to rebuke Abraham. It reveals Abraham's character and the influence of worldly associations upon a good man. The verse belongs to God's providential dealings with the family of Abraham as the chosen progenitor of the Seed. It is part of the history of beginnings and of God's care for the Seed against the enemy's attempts to thwart His plan. Within the larger Genesis 12-21 account, human planning to secure the promised heir, including through Hagar, led to bondage and trouble rather than simple reliance on God's promise.

The chapter shows that God's moral standard and moral principles were known and could be violated and judged as sin long before the law was proclaimed at Sinai in the time of Moses. This included the prohibition of adultery and the requirement of the ninth commandment against deception. The account proves the marriage institution was already sacred long before Sinai. The seventh commandment guards its sacredness just as the fourth commandment guards the Sabbath, but its sanctity does not come from the Decalogue and belongs to the institution as made for man before the fall.