What does Psalm 37:2 mean?

The prior verse instructed Christians not to be anxious—literally "heated up"—by the actions of evildoers. Their actions will eventually lead to disaster (Mark 8:36). In that sense, the wicked will not always be around. Soon they will fade away like the grass and wither like vegetation.

In the Middle East, where David lived, grass and vegetation thrives in the rainy season, but it disappears when rain no longer falls, and a hot sun scorches the earth. Isaiah 40:6–7 reminds us, "All flesh is grass, and all its beauty is like the flower of the field. The grass withers, the flower fades." The apostle James points out in James 4:14 that all life is temporal. He compares it to "a mist that appears for a little time and then vanishes." When the Israelites journeyed through the wilderness, they learned how brief life is. They saw a whole generation die there because they refused to believe God who commanded them to enter the Promised Land. Life is too brief to waste time being anxious over evildoers (Matthew 6:25–34).