[Sherman Logan]

True. Not claiming Abraham behaved badly, by the standards of his time.

You can read all through the OT, and not find a trace of the notion that a married man is obligated to be sexually faithful to his wife. Adultery in the OT is defined as sex with a married woman other than your wife. NOT as a married man having sex with an unmarried woman.

The NT is, of course, quite different in this regard.

[Raycpa]

I'm not claiming Abraham did not "behave badly". He took measures into his own hands when God promised otherwise. Based on Abraham's advanced age and his desire for offspring and his wife's solution it seems apparent that up until lying with Hagar he only had sex with his wife. My claim is Hagar was not a wife or a lover in modern terms but rather a surrogate chosen by both wife and husband. We also have no mention of Abraham have relations with anyone but his wife or Hagar.

Scripture (Gen 16) follows:

Hagar and Ishmael 16 Now Sarai, Abram’s wife, had borne him no children. But she had an Egyptian slave named Hagar; 2 so she said to Abram, “The Lord has kept me from having children. Go, sleep with my slave; perhaps I can build a family through her.” Abram agreed to what Sarai said. 3 So after Abram had been living in Canaan ten years, Sarai his wife took her Egyptian slave Hagar and gave her to her husband to be his wife. 4 He slept with Hagar, and she conceived.

Wikopedia defines surrogacy as follows:

A surrogacy arrangement or surrogacy agreement is the carrying of a pregnancy for intended parents.