That led them through the deep,.... The depths, the bottom of the sea; not through the shallow, but where the waters had been deepest, the descent greatest; and at the bottom of which might have been expected much filth and dirt to hinder them in their passage, yet through this he led them:as an horse in the wilderness; or rather, "in a plain", as the word sometimes signifies; and so Kimchi renders it a plain land, and Jarchi smooth land.
The sense is, that the Israelites passed through the sea with as much ease, and as little difficulty, as a good horse will run over a plain, where there is nothing to stop his course:that they should not stumble?
there being no clay to stick in, no stone to stumble at, but all like an even plain.