Sing unto God, sing praises to his name - That is, to him; the name being often put for the person himself. The repetition denotes intensity of desire; a wish that God might be praised with the highest praises.
Extol him - The word here rendered “extol” - סלל sâlal - means to lift up, to raise, to raise up, as into a heap or mound; and especially to cast up and prepare a way, or to make a way level before an army by casting up earth; that is, to prepare a way for an army. See the notes at Isaiah 40:3. Compare also Isaiah 57:14; Isaiah 62:10; Job 19:12; Job 30:12, Proverbs 15:19 (margin); Jeremiah 18:15. This is evidently the idea here. It is not to “extol” God in the sense of praising him; it is to prepare the way before him, as of one marching at the head of his armies, or as a leader of his hosts. The allusion is to God as passing before his people in the march to the promised land; and the call is to make ready the way before him - that is, to remove all obstructions out of his path and to make the road smooth and level.
That rideth - Rather,” that marcheth.” There is, indeed, the idea of riding, yet it is not that of “riding upon the heavens,” which is the meaning, but of riding at the head of his hosts on their march.
Upon the heavens - The word used here - ערבה ‛ărābâh - never means either heaven, or the clouds. It properly denotes an arid tract, a sterile region, a desert; and then, a plain. It is rendered desert in Isaiah 35:1, Isaiah 35:6; Isaiah 40:3; Isaiah 41:19; Isaiah 51:3; Jeremiah 2:6; Jeremiah 17:6; Jeremiah 50:12; Ezekiel 47:8; and should have been so rendered here. So it is translated by DeWette, Prof. Alexander, and others. The Septuagint renders it, “Make way for him who is riding westward.” So the Latin Vulgate. The Chaldee renders it, “Extol him who is seated upon the throne of his glory in the north heaven.” The reference, doubtless, is to the passage through the desert over which the Hebrews wandered for forty years. The Hebrew word which is employed here is still applied by the Arabs to that region. The idea is that of Yahweh marching over those deserts at the head of his armies, and the call is to prepare a way for him on his march, compare Psalms 68:7-8.
By his name JAH - This refers to his riding or marching at the head of his forces through the desert, in the character described by that name - or, as יה Yâhh; that is, יהוה Yahweh. Yah (Jah) is an abbreviation of the word Yahweh (Jehovah), which was assumed by God as His special name, Exodus 6:3. The word Yahweh is usually rendered, in our version, Lord, printed in small capitals to denote that the original is יהוה Yahweh; the word itself is retained, however, in Exodus 6:3; Psalms 83:18; Isaiah 12:2 (see the notes); and Isaiah 26:4. The word “Jah” occurs in this place only, in our English translation. It is found in combination, or in certain formulas - as in the phrase Hallelujah, Psalms 104:35; Psalms 105:45; Psalms 106:1. The meaning here is, that God went thus before His people in the character of the true God, or as Yahweh.
And rejoice before him - Or, in His presence. Let there be joy when He thus manifests Himself as the true God. The presence of God is suited to give joy to all the worlds that He has made, or wherever He manifests Himself to His creatures.