A.T. Robertson Commentary 1 Corinthians 16:3

"And when I arrive, whomsoever ye shall approve, them will I send with letters to carry your bounty unto Jerusalem:" — 1 Corinthians 16:3 (ASV)

When I arrive (οταν παραγενωμα). Whenever I arrive, indefinite temporal conjunction οταν and second aorist middle subjunctive.

Whomsoever ye shall approve by letters (ους εαν δοκιμασητε δι' επιστολων). Indefinite relative with εαν and aorist subjunctive of δοκιμαζω (to test and so approve as in Php 1:10). "By letters" to make it formal and regular and Paul would approve their choice of messengers to go with him to Jerusalem (2 Corinthians 8:20ff.). Curiously enough no names from Corinth occur in the list in Ac 20:4.

To carry (απενεγκειν). Second aorist active infinitive of αποφερω, to bear away.

Bounty (χαριν). Gift, grace, as in 2 Corinthians 8:4–7. As a matter of fact, the messengers of the churches (αποστολο εκκλησιων 2 Corinthians 8:23) went along with Paul to Jerusalem (Acts 20:4f.).