Psalm 1:4

The ungodly are not so,
But are like the chaff which the wind drives away.

Here we have a contrast with verse 3. "Not so" contrasts the state of righteous who meditate on God's Torah. The ungodly are not like ever fruitful trees. Whatever they do does not prosper.

'Like the chaff': Chaff is refuse that is blown away by the wind. It is what is separated from the wheat at harvest. This is similar to the imagery of the separation of the goats and sheep in the Olivet Discourse. Matthew 25:31-46. The righteous shall stand firm in the judgment. The wicked will be blown away.

'the wind': Hebrew, ruach. This word also means 'spirit.' The ruach ha'kodesh is the Holy Spirit. The ruach ha'elohim is the Spirit of God. God's spirit will drive away the wicked. If you would be firmly planted like a tree and not be harassed like a driven leaf (Job 13:25), spend your time in Torah. It is by meditating on His Word that you will have much success and that you will prosper. See Joshua 1:7-8.