ROMANS 4

18 even though there was no physical reason for him to hope that he would have descendants, because he and his wife were too old to bear children. But God is the one who causes dead people to live again, and who talks about things that do not yet exist as already existing. God said to Abraham, "You will have so many descendants that they will be as impossible to count as the stars." And Abraham believed that, and he believed that he would become the ancestor of many ethnic groups.