Charles Ellicott Commentary Psalms 37:1

"Fret not thyself because of evil-doers, Neither be thou envious against them that work unrighteousness." — Psalms 37:1 (ASV)

Fret ... —This verb, repeated in Psalm 37:7-8, is otherwise found only in Proverbs 24:19. Its meaning is to heat or inflame oneself.

Neither be thou envious ... —This has a similar root-meaning (compare our “burn with jealousy”), and so is in close parallelism with “fret.” This verse occurs almost word for word in Proverbs 3:31; Proverbs 23:16; Proverbs 24:1; and Psalm 73:3.