Jamieson, Fausset and Brown on 1 Corinthians 4:5

5. Disproving the judicial power claimed by the Romish priesthood in the confessional.

Therefore--as the Lord is the sole Decider or Dijudicator.

judge--not the same Greek word as in 1Co 4:3, 4, where the meaning is to approve of or decide on, the merits of one's case. Here all judgments in general are forbidden, which would, on our part, presumptuously forestall God's prerogative of final judgment.

Lord--Jesus Christ, whose "ministers" we are (1Co 4:1), and who is to be the judge (Joh 5:22, 27; Ac 10:42; 17:31).

manifest ... hearts--Our judgments now (as those of the Corinthians respecting their teachers) are necessarily defective; as we only see the outward act, we cannot see the motives of "hearts." "Faithfulness" (1Co 4:2) will hereby be estimated, and the "Lord" will "justify," or the reverse (1Co 4:4), according to the state of the heart.

then shall every man have praise--(1Co 3:8; 1Sa 26:23; Mt 25:21, 23, 28). Rather, "his due praise," not exaggerated praise, such as the Corinthians heaped on favorite teachers; "the praise" (so the Greek) due for acts estimated by the motives. "Then," not before: therefore wait till then (Jas 5:7).