Adam Clarke's Commentary on the Bible

Verse 4 (Deuteronomy 32:4)

He is the Rock - The word צור tsur is rendered Creator by some eminent critics; and khalyk is the reading in the Arabic Version. Rab. Moses ben Maimon, in his valuable work, Moreh Nebochim, observes that the word צור tsur , which is ordinarily translated rock, signifies origin, fountain, first cause, etc., and in this way it should be translated here: "He is the first principle, his work is perfect." As he is the cause of all things, he must be infinitely perfect; and consequently all his works must be perfect in their respective kinds. As is the cause, so must the effect be. Some think the word rock gives a very good sense: for, as in those lands, rocks were the ordinary places of defense and security, God may be metaphorically represented thus, to signify his protection of his followers. I prefer the opinion of Maimon.

- Adam Clarke's Commentary on the Bible