Charles Ellicott Commentary Romans 2:18

"and knowest his will, and approvest the things that are excellent, being instructed out of the law," — Romans 2:18 (ASV)

His will.—Literally, the will—i.e., "the supreme will."

Approvest the things that are more excellent.—Probably rightly given in the Authorised version, though the marginal rendering also is possible, "triest the things that differ"—i.e., "are able to discriminate between good and evil."

Being instructed.—With reference to the constant reading of the Law in the synagogue.