Romans 4:11-12

11And he received the sign of circumcision as a seal of the righteousness that he had by faith while still uncircumcised. This was to make him the father of all who believe but are not circumcised, so that righteousness may be credited to them also.

12And he became the father of the circumcised, who are not only circumcised but who also follow in the footsteps of the faith our father Abraham had while he was still uncircumcised.