Endureth (υπομενε). Present active indicative of υπομενω. Cf. verse James 1:3.
Temptation (πειρασμον). Real temptation here. See verse James 1:2 for "trials."
When he hath been approved (δοκιμος γενομενος). "Having become approved," with direct reference to το δοκιμιον in verse James 1:3. See also Romans 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 Revelation 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 (Psalm 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).