Romans 2:14

2:14 For whenever the Gentiles, who do not have the law, do by nature the things required by the law, these who do not have the law are a law to themselves.

Romans 2:26-27

2:26 Therefore if the uncircumcised man obeys the righteous requirements of the law, will not his uncircumcision be regarded as circumcision? 2:27 And will not the physically uncircumcised man who keeps the law judge you who, despite the written code and circumcision, transgress the law?