And he received the sign of circumcision, a seal of the righteousness of the faith which he had yet being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also:
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Tertullian of Carthage
AD 220
But you Jews say that Abraham was circumcised. Yes, but he pleased God before his circumcision, and he did not yet observe the sabbath. For he had accepted circumcision as a sign for that time, not as a prerogative title to salvation.