Galatians 4:26-28

26But the Jerusalem above [that is, the way of faith, represented by Sarah] is free; she is our mother.

27For it is written [in the Scriptures], “Rejoice, o barren woman who has not given birth; Break forth into a [joyful] shout, you who are not in labor; For the desolate woman has many more children Than she who has a husband.”

28And we, [believing] brothers and sisters, like Isaac, are children [not merely of physical descent, like Ishmael, but are children born] of promise [born miraculously].