For the horse ... - This verse does not belong to the hymn, but marks the transition from it to the narrative.

Exodus 15:19 Parallel Commentaries

Sixth Day. Holiness and Glory.
Who is like unto Thee, O Lord! among the gods? Who is like unto Thee, glorious in holiness, Fearful in praises, doing wonders? Thou in Thy mercy hast led Thy people which Thou hast redeemed: Thou hast guided them in Thy strength to the habitation of Thy holiness ... The holy place, O Lord, which Thy hands have established.' --Ex. xv. 11-17. In these words we have another step in advance in the revelation of Holiness. We have here for the first time Holiness predicated of God Himself. He …
Andrew Murray—Holy in Christ

The Old Testament Canon from Its Beginning to Its Close.
The first important part of the Old Testament put together as a whole was the Pentateuch, or rather, the five books of Moses and Joshua. This was preceded by smaller documents, which one or more redactors embodied in it. The earliest things committed to writing were probably the ten words proceeding from Moses himself, afterwards enlarged into the ten commandments which exist at present in two recensions (Exod. xx., Deut. v.) It is true that we have the oldest form of the decalogue from the Jehovist …
Samuel Davidson—The Canon of the Bible

The Publication of the Gospel
The Lord gave the word: great was the company of those that published it [or of the preachers] P erhaps no one Psalm has given greater exercise to the skill and patience of commentators and critics, than the sixty-eighth. I suppose the difficulties do not properly belong to the Psalm, but arise from our ignorance of various circumstances to which the Psalmist alludes; which probably were, at that time, generally known and understood. The first verse is the same with the stated form of benediction …
John Newton—Messiah Vol. 2