Romans 4:12

4:12 And he is also the father of the circumcised, who are not only circumcised, but who also walk in the footsteps of the faith that our father Abraham possessed when he was still uncircumcised.

Romans 4:16-21

4:16 For this reason it is by faith so that it may be by grace, with the result that the promise may be certain to all the descendants – not only to those who are under the law, but also to those who have the faith of Abraham, who is the father of us all 4:17 (as it is written, “I have made you the father of many nations”). He is our father in the presence of God whom he believed – the God who makes the dead alive and summons the things that do not yet exist as though they already do. 4:18 Against hope Abraham believed in hope with the result that he became the father of many nations according to the pronouncement, “so will your descendants be.” 4:19 Without being weak in faith, he considered his own body as dead (because he was about one hundred years old) and the deadness of Sarah’s womb. 4:20 He did not waver in unbelief about the promise of God but was strengthened in faith, giving glory to God. 4:21 He was fully convinced that what God promised he was also able to do.