A.T. Robertson Commentary 2 Corinthians 2:9

"For to this end also did I write, that I might know the proof of you, whether ye are obedient in all things." — 2 Corinthians 2:9 (ASV)

That I might know the proof of you (ινα γνω την δοκιμην υμων). Ingressive second aorist active subjunctive, come to know. Δοκιμη is proof by testing. Late word from δοκιμος and is in Dioscorides, medical writer in reign of Hadrian. Earliest use in Paul and only in him in N.T. (2 Corinthians 2:9; 2 Corinthians 8:2; 2 Corinthians 9:13; 2 Corinthians 13:3; Romans 5:4).

Obedient (υπηκοο). Old word from υπακουω, to give ear. In N.T. only in Paul (2 Corinthians 2:9; Acts 7:39).