A.T. Robertson Commentary James 1:12

"Blessed is the man that endureth temptation; for when he hath been approved, he shall receive the crown of life, which [the Lord] promised to them that love him." — James 1:12 (ASV)

Endureth (υπομενε). Present active indicative of υπομενω. Cf. verse 3.Temptation (πειρασμον). Real temptation here. See verse 2 for "trials."

When he hath been approved (δοκιμος γενομενος). "Having become approved," with direct reference to το δοκιμιον in verse 3. See also Ro 5:4 for δοκιμη (approval after test as of gold or silver). This beatitude (μακαριος) is for the one who has come out unscathed. See 1 Timothy 6:9.

The crown of life (τον στεφανον της ζωης). The same phrase occurs in Re 2:10. It is the genitive of apposition, life itself being the crown as in 1 Peter 5:4. This crown is "an honourable ornament" (Ropes), with possibly no reference to the victor's crown (garland of leaves) as with Paul in 1 Corinthians 9:25; 2 Timothy 4:8, nor to the linen fillet (διαδημα) of royalty (Psalms 20:3, where στεφανος is used like διαδημα, the kingly crown). Στεφανος has a variety of uses. Cf. the thorn chaplet on Jesus (Matthew 27:29).

The Lord . Not in the oldest Greek MSS., but clearly implied as the subject of επηγγειλατο (he promised , first aorist middle indicative).