Exodus 4:3; Exodus 7:15

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.
15 Get thee unto Pharaoh in the morning; lo, he goeth out unto the water; and thou shalt stand by the river's brink against he come ; and the rod which was turned to a serpent shalt thou take in thine hand.