William Burkitt on Romans 2:13

That is, not the bare hearers of the law shall, upon that account, be just before God, but the doers of the law shall be justified; that is, accepted of God, as acting suitable to their holy profession. It is notoriously known, that Jews gloried in, and rested upon, their outward privleges for salvation, because they were Abraham's seed, because they were circumcised, because they were employed in reading and hearing of the law; they concluded this sufficient to render them acceptable with God; therefore, says the apostle, not the hearers, but the doers of the law shall be justified; that is, the persons whom God will accept and account righteous for the sake of Christ.

Note here, That the doers of the law or word of God, are the best hearers, yea, the only hearers in the account of God. Hearing is good, but it must not be rested in; a great understanding may a man have by much reading the word and law of God; but a good understanding only have they that do the word and will of God; the praise and fruit of that endureth forever. Ps 111:10