Galatians 4:27-31

27It says in the Bible: ‘Be happy, you woman who could not have any children! You have never known the pain of a child's birth. But now shout loudly because you are so happy! Yes, be happy, because the lonely woman now has more children than the woman who has a husband.’

28You, my Christian friends, are like Sarah's son, Isaac. Like him, you became God's children as a result of God's promise.

29Isaac was born because of God's Spirit. The son who was born in the human way gave much trouble to Isaac at that time. You who are believers receive the same kind of trouble now.

30But this is what it says in the Bible: ‘Send away the woman who is a slave and her son. That woman's son will never receive anything from his father. The son of the free woman will receive all those good things.’

31So then, my Christian friends, we are not children of the woman who is a slave. No, we are children of the free woman.