Romans 4:16-18

16This is why the promise is by faith, so that it may be according to grace, to guarantee it to all the descendants  — not only to the one who is of the law but also to the one who is of Abraham’s faith. He is the father of us all.

17As it is written: I have made you the father of many nations  — in the presence of the God in whom he believed, the one who gives life to the dead and calls things into existence that do not exist.

18He believed, hoping against hope, so that he became the father of many nations according to what had been spoken: So will your descendants be.