“Tell me, you who want to be under the law, do you not understand the law? For it is written that Abraham had two sons, one by the slave woman and the other by the free woman” (Galatians 4:21-22).
Following Abraham’s decision to accept his wife Sarah’s advice to marry a maidservant named Hagar, Genesis 16:3-4 tells us that Hagar became pregnant with Abraham’s child. Upon learning of her pregnancy, Hagar began to treat Sarah (who was childless) with an attitude of contempt. In light of these circumstances, it shouldn’t come as a surprise to learn that a confrontation soon followed…
“Then Sarai said to Abram, ‘You are responsible for the wrong I am suffering. I put my servant in your arms, and now that she knows she is pregnant, she despises me. May the LORD judge between you and me'” (Genesis 16:5).
Another translation of this passage renders this confrontation in the following manner: “So Sarai complained to Abram, ‘I’m being treated unfairly! And it’s your fault! I know that I gave my slave to you, but now that she’s pregnant, she’s being disrespectful to me. May the LORD decide who is right- you or me'” (Genesis 16:5 GW).
So even though Abraham followed Sarah’s counsel, Sarah held him accountable for Hagar’s new attitude of disrespect. Of course, Abraham might have avoided this confrontation if he had chosen to seek God’s direction before acting on Sarah’s advice to marry the maid and have a child with her. Once again, this serves to illustrate the problem that may occur whenever we fail to seek God’s direction in the process of making decisions. If things go wrong as a result, we may end up taking the blame for another person’s bad idea. (1)
So the concluding verses of Galatians chapter four make use of these historical events to personalize the distinction between the Law and the freedom we have in Christ. While Abraham’s son through Hagar was born as a result of a human-oriented plan, the son who will eventually come through Sarah was a product of God’s provision.
Although this account may not seem to have much bearing on the discussion of faith vs. the Law that occurs here in Galatians chapters three and four, it serves to communicate something important. The point is that we may be in danger of joining the wrong branch of Abraham’s family tree if seek to find acceptance with God through the works of the Law and a human-oriented plan of salvation. (2)
(1) See 2 Chronicles 18:1-19:3 for the account of a similar blunder that cost the life of an Old Testament king of Israel and earned the Lord’s rebuke for a king of Judah
(2) See Constable, Thomas. DD. “Commentary on Galatians 4:4”. [Verses 21-31] “Expository Notes of Dr. Thomas Constable”. https://www.studylight.org/commentaries/dcc/galatians-4.html. 2012.