Albert Barnes Commentary Psalms 99:5

"Exalt ye Jehovah our God, And worship at his footstool: Holy is he." — Psalms 99:5 (ASV)

Exalt ye the Lord our God - See the notes at (Psalms 30:1). The meaning is, let his name be, as it were, lifted up on high, so as to be conspicuous or seen from afar. Let it be done with a lofty voice; let it be with ascriptions of praise.

And worship at his footstool - By humble prostration at his feet. The footstool is that on which the feet rest when one is sitting, and the reference here is to the footstool on which the feet of a king rested when he sat on his throne or chair of state. To worship at his footstool—(Compare to 1 Chronicles 28:2; Psalms 132:7)—denotes the deepest humility and the profoundest prostration and reverence.

It is as if we could not look on his face, or on his throne, or on his gorgeous and magnificent robes, but bowed our heads in lowly reverence, and deemed it sufficient honor to lie low before that on which his feet rested.

To show the dignity and majesty of God, the earth itself is represented as being merely his footstool; as being, in comparison with heaven—the place of his seat, his “throne”—only as the footstool is when compared to the splendid chair of state (Isaiah 66:1; Matthew 5:34–35).

For he is holy - . Margin, “it is holy.” The translation in the text best expresses the sense. The fact that God is “holy” is a reason for lowly and profound prostration before him.