A.T. Robertson Commentary 1 Thessalonians 5:28

"The grace of our Lord Jesus Christ be with you." — 1 Thessalonians 5:28 (ASV)

The grace (η χαρις). Paul prefers this noble word to the customary ερρωσθε (Farewell, Be strong). See 2 Thessalonians 3:18 for identical close save added παντων (all). A bit shorter form in 1 Corinthians 16:23; Romans 16:20 and still shorter in Col 4:18; 1 Timothy 6:21; Titus 3:15; 2 Timothy 4:22. The full Trinitarian benediction we find in 2 Corinthians 13:13.