What does 1 Corinthians 4:3 mean?

Paul has described himself and other Christian teachers who have ministered to the Corinthians as stewards of the revealed mysteries of God. They are servants assigned to the task of delivering the gospel message, among other things. Paul has been urging the Christians to be united in following Christ instead of bickering about to which Christian teacher they should pledge loyalty.

The role of a steward—a servant who manages his master's property—is an important one. Stewards must be found to be faithful people of high integrity, working with excellence and honesty.

Paul is aware that the Corinthians and others have put themselves in the place of judging the worthiness of Paul, Apollos, Peter, and other ministers and deciding if they are faithful enough. Paul now shrugs off their judgment, calling it a very small thing to be judged by them or even by a human court.

It's not that Paul is declaring himself above their judgments because of his position as an apostle or even because he is convinced of his own excellent performance. He will make clear in the following verses that their judgments don't matter because they are not the judge. The Lord will judge him, and it is pointless to speculate about what that judgment will be before the moment arrives.

Paul adds that he is not even qualified to judge himself. Who would know Paul's motives and effectiveness better than Paul? If he cannot adequately judge himself, why should he worry about the opinions of human judges? That doesn't mean Paul is claiming to be perfect, as the next verse will show.