Romans 4:11-12

11And he received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. So then, he is the father of all who believe but are not circumcised, in order that righteousness might be credited to them. 12And he is also the father of the circumcised who not only are circumcised, but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.