And the Lord spake unto Moses and unto Aaron After he had given them their commission, and instructions to go to Pharaoh, and a little before they went in to him:
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."
10
Moses 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.