The psalmist explains that those who delight in God’s law and not the world are blessed.
They continue to explain that those who dwell in him constantly will be strong like a tree next to a river. They will also be fruitful and bear fruit. All they do in the Lord will be made to prosper.
This is extremely positive and encouraging, but the second half, however, admonishes. It says those who are ungodly are not so. In metaphors it explains they become vain and useless and shall not stand in judgement.
(Verse 6) “For the Lord knoweth the way of the righteous: but the way of the ungodly shall perish.” So, are you a tree who will stand strong or the chaff which the wind drives away, vain and useless?