In the preceding chapter, Genesis 15, the Lord had told Abram four times that he would have a descendant:
- 15:4 - “This man will not be your heir, but a son coming from your own body will be your heir.”
- 15:5 - “Look up at the heavens and count the stars...So shall your offspring be.”
- 15:13 - "Your descendants will be strangers in a country not their own, and they will be enslaved and mistreated four hundred years."
- 15:18 - “To your descendants I give this land, from the river of Egypt to the great river, the Euphrates."
Ancient documents from around this time period, 2000 BC, attest to the reality of the accepted practice of using a slave to bear children in the case of barrenness. Four common sources of this practice are cited in Hammurabi's Code (go here and scroll to #146), an Assyrian marriage contract, a Nuzi text, and a Neo-Assyrian text.
One of the records mentioned above, the Old Assyrian marriage contract, sets the limit for time allowed for waiting for a wife to get pregnant was two years. After two years the woman was expected to buy a maid-servant to bear a child. Abram and Sarah have been in the land of Canaan now for ten years. Sarai's actions may actually have been up to eight or more years late. The rabbi's taught that ten years of barrenness was reason enough for a man to divorce his wife, thus the rabbi's taught, Sari was avoiding a divorce or being forced to share her favored position of "wife" with another woman. It seems from the ancient records and from Sarai's own words that the woman initiated this process.
The literal reading of the Hebrew says "he obeyed Sarai's voice." The wording is similar to Adam obeying Eve in Genesis 3:17. In this case God is not going to recognize Hagar's son as an option and, definitely, not the fulfillment of God's promise. Hagar, Sarai and Abram will all have to pay the price for having followed the culturally accepted ways and assuming that social accepted practices are the same as obedience to the promises of God's word.