That I might know the proof of you (hina gnō tēn dokimēn humōn). Ingressive second aorist active subjunctive, come to know. Dokimē is proof by testing. Late word from dokimos and is in Dioscorides, medical writer in reign of Hadrian. Earliest use in Paul and only in him in N.T. (2Co 2:9; 2Co 8:2; 2Co 9:13; 2Co 13:3; Rom 5:4; Phi 2:22).
Obedient (hupēkooi). Old word from hupakouō, to give ear. In N.T. only in Paul (2Co 2:9; Phi 2:8; Act 7:39).