Galatians 4:22-26 New Revised Standard Version (NRSV)
22 For it is written that Abraham had two sons, one by a slave woman and the other by a free woman. 23 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. 24 Now this is an allegory: these women are two covenants. One woman, in fact, is Hagar, from Mount Sinai, bearing children for slavery. 25 Now Hagar is Mount Sinai in Arabia[a] and corresponds to the present Jerusalem, for she is in slavery with her children. 26 But the other woman corresponds to the Jerusalem above; she is free, and she is our mother.