10Now if Timothy comes, see that he is with you without cause to be afraid, for he is doing the Lord's work, as I also am. 11So let no one despise him. But send him on his way in peace, so that he may come to me; for I expect him with the brethren.
1Co_16:10 "if" This is a third class conditional sentence, meaning potential action. It seems that Paul had already sent Timothy and Erastus (cf. Act_19:22), and possibly Titus (cf. 2Co_2:13; 2Co_7:6-7) on to Corinth by the land route. He was sending his letter by sea and it would arrive quicker.
▣ "see that he is with you without cause to be afraid" Paul puts this in the form of a command (i.e., present active imperative). He knew personally how unloving the church could be. He did not want his young assistant to be slighted because of (1) his age; (2) his personality; or (3) their anger toward Paul (cf. 1Co_16:11).
1Co_16:11
NASB, NKJV,
NRSV
"So let no one despise him"
TEV
"No one should look down on him"
NJB
"nobody is to underrate him"
This is an aorist active subjunctive, which literally means "to make absolute nothing of" (cf. 1Co_1:28; 1Ti_4:12; Tit_2:15).
▣ "with the brethren" We are not sure who this involved. It may possibly be Erastus (cf. Act_19:22, and Titus, 2Co_2:13; 2Co_7:6-7), but who else, if anyone, is uncertain.