Galatians 4:21-31 - Hagar And Sarah Represent Two Covenants
21 Tell me this, you who want to be subject to law: Will you not listen to the Law? 22 For the Scripture says that Abraham had two sons, one by the slave-girl, and one by the free woman. 23 But the child of the slave-girl was born in the ordinary course of nature, while the child of the free woman was born in fulfilment of the promise. 24 This is an allegorical utterance. For the women are two agreements, one coming from Mount Sinai, bearing children that are to be slaves; that is, Hagar 25 (and Hagar means Mount Sinai, in Arabia), and corresponds to the present Jerusalem, for Jerusalem is in slavery with her children. 26 But the Jerusalem above is free, and she is our mother. 27 For the Scripture says, "Rejoice, childless woman, who bear no children, Break into shouting, you who have no birth pains! For the desolate woman has more children than the married one!"
28 Now we, brothers, are like Isaac, children born in fulfilment of the promise. 29 But just as then the child born in the ordinary course of nature persecuted the one born through the influence of the Spirit, so it is today. 30 Yet what does the Scripture say? "Drive the slave-girl and her son away, for the slave-girl's son shall not share the inheritance with the son of the free woman."
31 So, brothers, we are children not of a slave but of one who is free.