Exodus 7:8-11

8The Lord said to Moses and Aaron,

9“When Pharaoh says to you, ‘Give me a sign to prove that God has sent you,’ tell Aaron, ‘Take your shepherd’s staff and throw it down in front of Pharaoh,’ and it will become a large snake.”

10Moses and Aaron went to Pharaoh and did as the Lord had commanded. Aaron threw his staff down in front of Pharaoh and his officials, and it became a large snake.

11Then Pharaoh sent for his wise men and sorcerers. These Egyptian magicians did the same thing using their magic spells.