Romans 4:13-18, 20-21 (NRSV)
13 The promise that he would inherit the world did not come to Abraham or to his descendants through the law but through the righteousness of faith. 14 If it is the adherents of the law who are to be the heirs, faith is null and the promise is void. 15 For the law brings wrath; but where there is no law, neither is there violation. 16 For this reason it depends on faith, in order that the promise may rest on grace and be guaranteed to all his descendants, not only to the adherents of the law but also to those who share the faith of Abraham (for he is the father of all of us, 17 as it is written, “I have made you the father of many nations”) –in the presence of the God in whom he believed, who gives life to the dead and calls into existence the things that do not exist. 18 Hoping against hope, he believed that he would become “the father of many nations,” according to what was said, “So numerous shall your descendants be.” 20 No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, 21 being fully convinced that God was able to do what he had promised.