This song is verbal clip-art; it is a collection of quotations from other psalms and songs from the historical books of the Old Testament. Artfully woven together in this new format, it was probably a responsive psalm, but there is no solid consensus among scholars on the voices and parts. Still, it clearly offers a rousing thanksgiving celebration.
The first line is an imperative: Praise Jehovah! The root meaning of the verb “praise” is to draw a sharp contrast, to make something stand out. We exist for His glory. It is our power to live and nothing can answer the deep need of the human soul like rendering praise to our Maker. You need a reason? He has chosen us as His special treasure on the earth.
Keep in mind that this all stands in the frame of reference where Jehovah is the imperial ruler, a feudal sheik. The psalmist forcefully claims to know this Lord personally. Is there any other sheik like Him? Who else could have his whims from Creation itself? Who else could devise the cycle of precipitation with the added glory of lightening? Who can hold or release the winds upon the earth at His whims?
For all the deep, ancient and mystical powers of Egypt and her vast pantheon of deities, Jehovah was able to put them all to shame. He ravaged Egypt like a weak young girl and none her deities could do a thing about it. Nor could any of the other gods along the Exodus stay His hand from taking what He wanted; kings died with their whole armies. Then He distributed the plundered land as an inheritance to His own tribe.
The earth could fade away into mist, but the reputation of God as Master of all Creation will stand eternally. Nobody can challenge His jurisdiction, and He ensures that His household gets special treatment in His justice.
Look at how the Gentile nations bow to things they have made with their own hands. God made those materials, and the hands to shaped them. Those deities only look like people, but they are blind, deaf and silent. They don’t even breathe, and you have to wonder about what kind of people would fall down and worship dead gods like that.
So the psalmist calls for the whole nation to confess their allegiance to Jehovah, and they echo back to the priests and Levites to do the same. If His eminence burns in your heart, how can you do any less? Is this not the God who has gathered us around His Temple here in Zion? Is there any other deity claiming to come and live with us this way? There is no room for loyalty to any other.