2 Timothy 1:12

For the which cause--For the Gospel cause of which I was appointed a preacher (Ti2 1:10-11). I also suffer--besides my active work as a missionary. ELLICOTT translates, "I suffer even these things"; the sufferings attendant on my being a prisoner (Ti2 1:8, Ti2 1:15). I am not ashamed--neither be thou (Ti2 1:8). for--Confidence as to the future drives away shame [BENGEL]. I know--though the world knows Him not (Joh 10:14; Joh 17:25). whom--I know what a faithful, promise-keeping God He is (Ti2 2:13). It is not, I know how I have believed, but, I know WHOM I have believed; a feeble faith may clasp a strong Saviour. believed--rather, "trusted"; carrying out the metaphor of a depositor depositing his pledge with one whom he trusts. am persuaded-- (Rom 8:38). he is able--in spite of so many foes around me. that which I have committed unto him--Greek, "my deposit"; the body, soul, and spirit, which I have deposited in God's safe keeping (Th1 5:23; Pe1 4:19). So Christ Himself in dying (Luk 23:46). "God deposits with us His word; we deposit with God our spirit" [GROTIUS]. There is one deposit (His revelation) committed by God to us, which we ought to keep (Ti2 1:13-14) and transmit to others (Ti2 2:2); there is another committed by God to us, which we should commit to His keeping, namely, ourselves and our heavenly portion. that day--the day of His appearing (Ti2 1:18; Ti2 4:8).

— Jamieson-Fausset-Brown Commentary (public domain)