Psalm 37:1–11 encourages David’s audience to maintain a proper relationship with God by refusing to wallow in anxiety over their circumstances.
David learned through personal experience that worshipful respect for God pushes out fear of those who do evil. His advice to other believers is to put aside worrying about evildoers. He also advises believers not to envy those who do wrong.
The word translated “fret” in this verse is from the Hebrew root word charah, meaning “to get heated up or to burn.” Had he been using English expressions, David might have counseled the righteous not to “get steamed,” or “hot under the collar” because of evildoers. The point is not that those who follow God ought to ignore sin; rather, it’s that we shouldn’t succumb to fear or despair (Matthew 6:25–34). Wicked people cannot cause our temperature to rise—for us to become truly anxious—unless we allow them to do so.
Also, those who believe the Lord cares for us regardless of what the wrongdoers have should not be envious. The writer to the Hebrews calls on us to maintain the right attitude toward material things. He wrote: “Keep your life free from the love of money, and be content with what you have, for he has said, ‘I will never leave you nor forsake you'” (Hebrews 13:5). Those who ignore God may think they are coming out ahead, when in fact they’re giving up eternity for the sake of something temporary (Mark 8:36).
It’s also true that the evil won’t always be there to harass the righteous, as the next verse makes clear (Psalm 37:2).