And the Lord said to Moses, put forth thy hand, and take it by the tail,.... Which to do might seem most dangerous, since it might turn upon him and bite him; this was ordered, partly that Moses might be assured it was really a serpent, and not in appearance only; and partly to try his courage, and it suggested to him, that he need not be afraid of it, it would not hurt him: the above learned doctor observes , that he is commanded to take it by the tail; for to meddle with the serpent's head belonged not to Moses, but to Christ that spake to him out of the bush:and he put forth his hand, and caught it, and it became a rod in his hand; as it was before.
Some think this refers to the threefold state of the Israelites, first to their flourishing estate under Joseph, when they were as a rod or staff, then to their dejected state, by this rod cast to the ground, and become a serpent, and lastly to their restoration and liberty, by its becoming a rod again: others refer it to Christ, who is the power of God, and the rod of his strength, and who in his state of humiliation was like this rod, cast to the ground and became a serpent, of which the brazen serpent was a type, and who by his resurrection from the dead regained his former power; but perhaps they may be most right who think it refers to the service and ministry of Moses, which seemed terrible to him at first, like a hurtful serpent, from which he fled; but after he was confirmed by the word of God, he readily undertook it.
De Vita Mosis, l. 1.