"May the wrong done me be upon you. I gave my maid into your arms, but when she saw that she had conceived, I was despised in her sight. May the LORD judge between you and me" (Genesis 16:5).
Distressed and broken-hearted, Sarah went to Abraham to lodge a complaint and to inquire about his intentions.
What would you do if you were Abraham? He had consented to the affair only at Sarah's behest. Now she comes lodging accusations at him, calling down curses on him and blaming him for her mistake. Most husbands would respond with a sharp rejoinder: "Hey, it was your bright idea, now it's your problem. Don't blame me." But Abraham was not like most husbands. Instead of returning Sarah's recriminations, he listened past the verbal abuse and heard the pain of her heart. She was wounded, hurting and desperately afraid of losing her husband to her maidservant.
Husbands ... live with your wives in an understanding way, as with someone weaker, since she is a woman; and show her honor as a fellow heir of the grace of life, so that your prayers will not be hindered. (1 Peter 3:7)
Learn from Abraham's example. Abraham saw that Hagar no longer considered herself Sarah's servant. She considered herself as Sarah's peer. He told Sarah, "Behold, your maid is in your power; do to her what is good in your sight" (Genesis 16:6). Abraham affirmed that Hagar was still subordinate to Sarah. Sarah had not been replaced by the younger woman in Abraham's eyes—and he passed the test by remaining true to his wife.
[copied from an FFOZ E-drash] it was just too good to pass up!