Romans 2:18

18 if you know his will and approve of what is superior because you are instructed by the law;

Read Romans 2:18 Using Other Translations

And knowest his will, and approvest the things that are more excellent, being instructed out of the law;
and know his will and approve what is excellent, because you are instructed from the law;
You know what he wants; you know what is right because you have been taught his law.