Sing praises... — Better, play on the harp.
Extol him that rideth upon the heavens. — Rather, cast up a highway for him that rideth on the steppes. (Comp. Isaiah 40:3, of which this is apparently an echo.) The poet’s voice is the herald’s who precedes the army of God to order the removal of all obstructions, and the formation of cairns to mark the road. Isaiah 57:14; Isaiah 62:10, are passages alluding to the same custom.
The translation, “upon the heavens,” rests on a rabbinical interpretation of ‘arabôth.
By derivation it means “a dry sandy region,” a “steppe.” The singular of the noun forms with the article a proper name designating the Jordan valley. (In the poetical books, however, any wild tract of country is called ‘Arabah — Isaiah 35:1; Isaiah 35:6.) The plural often designates particular parts of this region, as the plains of Moab or Jericho (2 Kings 25:4-5). Such a restricted sense is quite in keeping with the allusions to the early history which make up so much of the psalm.
By his name JAH. — Better, his name is Jah. This abbreviated form of Jehovah is first found in Exodus 15:2. No doubt the verse is a fragment of a song as old as the Exodus.
It may be noticed here that the dependence of this psalm on older songs is nowhere more conspicuous than in the very various use of the Divine names, Elohim, Adonai, El, Shaddai, Jehovah, Jah.