From First Corinthians by George T. Montague, SM, commenting on I Corinthians 3:16-23
Not wanting to speak for the other ministers (Peter or Apollos; see 1:12) but suggesting they would probably feel the same way, Paul first addresses those who would judge him. Your judgment, he says, does not concern me in the least.
Paul is not concerned by what people think of him. If he is concerned, as he has been for more than three chapters now, about the way they are comparing ministers, it is for the sake of the unity of the community and not because he sets any value on such judgments. I do not even pass judgment on myself. Paul is using judgment in two senses here: as the judgment of his conscience and as the judgment of the relative value of himself and the other ministers. As far as conscience is concerned, he is not conscious of anything against himself.
Although his conscience is clear, he does not judge himself acquitted, since anyone may have faults that he cannot see (Ps 19:13). He leaves that judgment to the Lord. So both for himself and in comparison with others, Paul refuses to judge.
His listeners should follow his example and not pass judgment on the relative value of the ministers. The Lord will do that at the appointed time: when the Lord comes. “There is nothing concealed that will not be revealed, nor secret that will not be known” (Luke 12:2). Even the greatest works of ministry done without love avail nothing (1 Cor 13:1–3), but that is for the Lord to judge, when he will bring to light what is hidden in darkness and will manifest the motives of our hearts.
Note that in saying then everyone will receive praise from God, Paul does not anticipate condemnation of any of these particular ministers (Peter, Apollos, or himself), only the relative degree of praise they will receive according to the value of the ministry they have performed, as in 3:10–14.