Romans 4:11

4:11 And he received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised, so that he would become the father of all those who believe but have never been circumcised, that they too could have righteousness credited to them.

Romans 7:7

7:7 What shall we say then? Is the law sin? Absolutely not! Certainly, I would not have known sin except through the law. For indeed I would not have known what it means to desire something belonging to someone else if the law had not said, “Do not covet.”