Albert Barnes Commentary Psalms 47:7

"For God is the King of all the earth: Sing ye praises with understanding." — Psalms 47:7 (ASV)

For God is the King of all the earth - He has shown Himself to be a universal sovereign. All nations are subject to Him, and He has a claim to universal praise.

Sing praises with understanding - Margin: "Every one that has understanding." However, neither the text here nor the margin expresses the true idea of the original. The Hebrew is, "Sing a Maschil" - משׂכיל maśkı̂yl; that is, sing or play a didactic psalm or tune; that is, a song or ode adapted to convey valuable lessons of instruction. See the word explained in the notes on the title of Psalms 32:1-11.

The idea is that the occasion was one for which such a psalm or song would be especially appropriate. It was an occasion on which God's dealings had taught great lessons or truths, which his people were now to set forth in a fitting manner.

These lessons or truths pertained to the fact that God is the great King over all the earth, or that He is a sovereign among the nations: a truth of immense importance to mankind, and a truth that the occasion on which the psalm was composed was especially adapted to highlight.