John Trapp on Psalms 37:8

Verſ. 8. Ceaſe from anger and forſake wrath] Repetitio eſt, ut mag is inculcet, ſaith Vatablus; This precept is doubled and redoubled, that we may the better retain and practiſe it. Angry a man may be, and muſt be at evil-doers, in as much as they break Gods Law, Pſal. 119.135. pollute his Name, Ezek. 36.20.23. Rom. 2.23, 24. procure the Judgments of God upon others alſo, Joſh. 22.18. pull down ſwift deſtruction upon themſelves, 2 Pet. 2.1. Romans 2.5. Thus Moſes was angry, Exod. 32.19. and our Saviour, Mark 3.5. yet not ſo angry but that they could at ſome time pity thoſe they were diſpleaſed with, and pray for them too. This they that cannot do, are inordinately and ſinfully angry, and muſt at any rate ſuppreſs ſuch paſſionate diſtempers.

Fret not thy ſelf in any miſe to do evil] And he ſhall have much a do not to overdo, not to do amiſs, that bridleth not his paſſions, for theſe, like heavie bodies down ſteep hills, once in motion, move themſelves, and ſeldom know any ground but the bottom. Ne igitur accendaris irâ ſaltem ad malefaciendum. Kimchi rendreth it, Ne miſce as teipſum, Come not in company with the ungodly, at leaſt to do evil; to do as they do. So to thoſe words in the firſt verſe, Eret net thy ſelf becauſe of evil-doers, the Chaldee addeth, to be like unto them.