It became a serpent Was really changed into a serpent. There was a significancy in this sign: it intimated what and how pernicious his rod would be to the Egyptians. It became a rod in his hand When stretched forth by the hand of Moses or Aaron, it became a token to Israel of guidance, encouragement, and protection; but to Egypt, like the bite of the most poisonous serpent, it betokened desolating judgments.
Related Commentaries of Exodus 4:3
Exodus 4:3-4
3 And he said, Cast it on the ground. And he cast it on the ground, and it became a serpent; and Moses fled from before it.
4 And the LORD said unto Moses, Put forth thine hand, and take it by the tail. And he put forth his hand, and caught it, and it became a rod in his hand: