Exodus 7:8-13

8And Jehovah spoke to Moses and to Aaron, saying,

9When Pharaoh shall speak to you, saying, Do a miracle for yourselves, — then thou shalt say unto Aaron, Take thy staff and cast [it] before Pharaoh — it will become a serpent.

10And Moses and Aaron went in to Pharaoh, and did so, as Jehovah had commanded; and Aaron cast down his staff before Pharaoh, and before his bondmen, and it became a serpent.

11And Pharaoh also called the sages and the sorcerers; and they too, the scribes of Egypt, did so with their enchantments:

12they cast down every man his staff, and they became serpents; but Aaron's staff swallowed up their staves.

13And Pharaoh's heart was stubborn, and he hearkened not to them, as Jehovah had said.