Jamieson, Fausset & Brown

it is a very small thing--literally, "it amounts to a very small matter"; not that I despise your judgment, but as compared with God's, it almost comes to nothing. judged . . . of man's judgment--literally, "man's day," contrasted with the day (Co1 3:13) of the Lord (Co1 4:5; Th1 5:4). "The day of man" is here put before us as a person [WAHL]. All days previous to the day of the Lord are man's days. EMESTI translates the thrice recurring Greek for "judged . . . judge . . . judgeth" (Co1 4:4), thus: To me for my part (though capable of being found faithful) it is a very small matter that I should be approved of by man's judgment; yea, I do not even assume the right of judgment and approving myself--but He that has the right, and is able to judge on my case (the Dijudicator), is the Lord.