Galatians 4:21-23

Some of you still want to be under the law. Tell me, do you know what the law says? The Scriptures say that Abraham had two sons. The mother of one son was a slave woman, and the mother of the other son was a free woman. Abraham’s son from the slave woman was born in the normal human way. But the son from the free woman was born because of the promise God made to Abraham.