Tell me, you who desire to be subject to the law, will you not listen to the law?
For it is written that Abraham had two sons, one by a slave woman and the other by a free woman.
One, the child of the slave, was born according to the flesh; the other, the child of the free woman, was born through the promise.
Now this is an allegory: these women are two covenants. One woman, in fact, is Hagar, from Mount Sinai, bearing children for slavery.
Now Hagar is Mount Sinai in Arabia and corresponds to the present Jerusalem, for she is in slavery with her children.
References for Galatians 4:25
But the other woman corresponds to the Jerusalem above; she is free, and she is our mother.
For it is written, "Rejoice, you childless one, you who bear no children, burst into song and shout, you who endure no birth pangs; for the children of the desolate woman are more numerous than the children of the one who is married."
Now you, my friends, are children of the promise, like Isaac.
References for Galatians 4:28
But just as at that time the child who was born according to the flesh persecuted the child who was born according to the Spirit, so it is now also.
But what does the scripture say? "Drive out the slave and her child; for the child of the slave will not share the inheritance with the child of the free woman."
So then, friends, we are children, not of the slave but of the free woman.
References for Galatians 4:31