Romans 4:11-14

and he received the sign of circumcision, a seal of the righteousness of the faith which he had while uncircumcised, so that he might be the father of all who believe without being circumcised, that righteousness might be credited to them, and the father of circumcision to those who not only are of the circumcision, but who also follow in the steps of the faith of our father Abraham which he had while uncircumcised. For the promise to Abraham or to his descendants that he would be heir of the world was not through the Law, but through the righteousness of faith. For if those who are of the Law are heirs, faith is made void and the promise is nullified