A.T. Robertson Commentary 2 Timothy 1:8

"Be not ashamed therefore of the testimony of our Lord, nor of me his prisoner: but suffer hardship with the gospel according to the power of God;" — 2 Timothy 1:8 (ASV)

Be not ashamed of (μη επαισχυνθηις). First aorist (ingressive) passive subjunctive (in prohibition) of επαισχυνομα, old word, to be ashamed. Again in verse 16 without augment (επαισχυνθην), transitive use of the passive voice as often in the Koine (Robertson, Grammar, p. 818). See Ro 1:16; 6:21. "Do not become ashamed" (as he had not).

The testimony of our Lord (το μαρτυριον του κυριου). For the old word μαρτυριον see 1 Corinthians 1:6; 2:1. Paul probably has in mind the saying of Jesus preserved in Mr 8:38 (Luke 9:26). See also 2:12.

His prisoner (τον δεσμιον αυτου). As in Php 1:12; Phm 1:1,9; Ephesians 3:1; 4:1 (the first Roman captivity). Paul is in his last captivity and refers to it again in verse 16; 2:9.

Suffer hardship with (συνκακοπαθησον). First aorist active imperative of the double compound συνκακοπαθεω, first known use and in N.T. only here and 2:3 (in eccles. writers). But κακοπαθεω, to suffer evil, is old verb (2:9; 4:5). Paul is fond of compounds of συν. Paul challenges Timothy by this verb which he apparently coins for the purpose to a joint (συν) suffering with the Lord Jesus and Paul "for the gospel" (τω ευαγγελιω, dative case rather than associative instrumental "with").

According to the power of God (κατα δυναμιν θεου). Given by God (2 Corinthians 6:7).