And Moses answered and said, But, behold, they will not believe me, nor hearken unto my voice: for they will say, The Lord hath not appeared unto thee.
And the Lord said unto him, What is that in thine hand? And he said, A rod.
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.
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:
That they may believe that the Lord God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath appeared...
Exodus 7: 7-16
And Moses was fourscore years old, and Aaron fourscore and three years old, when they spake unto Pharaoh.
And the Lord spake unto Moses and unto Aaron, saying,
When Pharaoh shall speak unto you, saying Shew a miracle for you: then thou shalt say unto Aaron, Take thy rod, and cast it before Pharaoh, and it shall become a serpent.
And Moses and Aaron went in unto Pharaoh, and they did so as the Lord had commanded: and Aaron cast down his rod before Pharaoh, and before his servants, and it became a serpent.
Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments.
For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods.
And he hardened Pharaoh's heart, that he hearkened not unto them: as the Lord had said.
And the Lord said unto Moses, Pharaoh's hear is hardened, he refuseth to let the people go.
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.