Albert Barnes Commentary 2 Corinthians 8:22

"and we have sent with them our brother, whom we have many times proved earnest in many things, but now much more earnest, by reason of the great confidence which [he hath] in you." — 2 Corinthians 8:22 (ASV)

And we have sent with them our brother. Who this was is completely unknown, and conjecture is useless. Some have supposed that it was Apollos, others Silas, others Timothy. But there is no way of ascertaining who it was, nor is it important. It was someone in whom Paul had complete confidence.

Whom we have often proved diligent. We have evidence that he has been faithful. It is evident, therefore, that he had been the companion and fellow laborer of Paul.

But now much more diligent, etc. He will now prove himself much more diligent than ever before.

Upon the great confidence, etc. The marginal reading is he hath. This is undoubtedly the more correct reading here. The idea is that this brother had great confidence in the Corinthians that they would give liberally, and that he would, therefore, show special diligence in the business.