Exodus 7:12

9 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.

10 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.

11 Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments.

12 For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods.

13 And he hardened Pharaoh's heart, that he hearkened not unto them; as the LORD had said.

14 And the LORD said unto Moses, Pharaoh's heart is hardened, he refuseth to let the people go.

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.