16:10-12 Timothy came to do the work of the Lord. Therefore to vex his spirit, would be to grieve the Holy Spirit; to despise him, would be to despise Him that sent him. Those who work the work of the Lord, should be treated with tenderness and respect. Faithful ministers will not be jealous of each other. It becomes the ministers of the gospel to show concern for each other's reputation and usefulness.
12. Apollos, I greatly desired … to come unto you—He says this lest they should suspect that he from jealousy prevented Apollos' coming to them; perhaps they had expressly requested Apollos to be sent to them. Apollos was not at Ephesus when Paul wrote (compare 1Co 16:19, and 1Co 1:1). Probably Apollos' unwillingness to go to Corinth at this time was because, being aware of the undue admiration of his rhetorical style which led astray many at Corinth, he did not wish to sanction it (1Co 1:12; 3:4). Paul's noble freedom from all selfish jealousy led him to urge Apollos to go; and, on the other hand, Apollos, having heard of the abuse of his name at Corinth to party purposes, perseveringly refused to go. Paul, of course, could not state in his letter particularly these reasons in the existing state of division prevalent there. He calls Apollos "brother" to mark the unity that was between the two.
with the brethren—who bear this letter (1Co 16:17). (See 1Co 16:24, subscription added to the Epistle). Conybeare thinks Titus was one of the bearers of this first letter (2Co 8:6, 16-24; 12:18). Alford thinks "the brethren" here may be the same as in 1Co 16:11.
convenient time—Apollos did return to Corinth when their divisions were moderated [Jerome], and so it was a more seasonable time.