Psalms 68:4

4. Extol him Hebrew, Cast up to him. The same word is used Isaiah 57:14; Isaiah 62:10, and elsewhere, for the levelling and smoothing (grading, as we would say) of public royal and military highways. The sense of “extol” exalt by praises is admissible, but the figure requires the sense of prepare, cast up, as of a highway for Jehovah.

Rideth upon the heavens Hebrew, Rideth ( בערבות , ba-Araboth) along the desert plains. The word is in the plural; the singular, Arabah, is the name anciently given to the great valley extending from the sources of the Jordan to the Gulf of Akaba, in Arabia, called modernly el-Ghor in its northern and Arabah in its southern half, (BURCKHARDT, Travels in Syria, pp. 441-443,) but may apply to any desert plain or steppe. It often occurs in Scripture, and is almost always translated plain, never “heaven,” except in this place. Desert plain is the idea, which here literally applies not only to the Arabah just mentioned, through the entire length of which the Israelites marched, (Deuteronomy 2:1-3,) but to the valleys and plains of Arabia as well. The imagery is military. Jehovah, the sovereign, marches through the lands where of old he led his people, and a suitable way should be prepared. A herald goes before and calls upon the tribes and nations to cast up a highway along the desert steppes. The figure is resumed in Psalms 68:7. The spiritual sense, without which the language is simply turgid, is found in Isaiah 40:3; Luke 3:4-5.

Jah A poetical form for Jehovah. Read Cast up [the way to] him who rides in the desert plains by his name Jah. This is his essential name.