And he said, cast it on the ground,.... That is, the rod or staff:and he cast it on the ground, and it became a serpent; not in appearance only, but in reality, it was changed into a real living serpent; for God, who is the author of nature, can change the nature of things as he pleases; nor is it to be supposed that he would only make it look to the sight as if it was one, by working upon the fancy and imagination to think it was one, when it was not; no doubt but it was as really turned into a true serpent, as the water was turned really and truly into wine by our Lord; this was the first miracle that ever was wrought, that we know of.
Dr. Lightfoot observes, that as a serpent was the fittest emblem of the devil, Ge 3:1 so was it a sign that Moses did not these miracles by the power of the devil, but had a power over and beyond him, when he could thus deal with the serpent at his pleasure, as to make his rod a serpent, and the serpent a rod, as he saw good:and Moses fled from before it; the Jews say it was a fiery serpent, but for this they have no warrant: however, without supposing that it might be terrible and frightful, inasmuch as a common serpent is very disagreeable to men, and such an uncommon and extraordinary one must be very surprising, to see a staff become a serpent, a living one, crawling and leaping about, and perhaps turning itself towards Moses, whose staff it had been.
Philo the Jew says, it was a dragon, an exceeding large one. Works, vol. 1. p. 702. Pirke Eliezer, c. 40. De Vita Mosls, l. 1.