Exodus 7:8-13

Then the LORD said to Moses and Aaron, “Pharaoh will demand, ‘Show me a miracle.’ When he does this, say to Aaron, ‘Take your staff and throw it down in front of Pharaoh, and it will become a serpent.’” So Moses and Aaron went to Pharaoh and did what the LORD had commanded them. Aaron threw down his staff before Pharaoh and his officials, and it became a serpent! Then Pharaoh called in his own wise men and sorcerers, and these Egyptian magicians did the same thing with their magic. They threw down their staffs, which also became serpents! But then Aaron’s staff swallowed up their staffs. Pharaoh’s heart, however, remained hard. He still refused to listen, just as the LORD had predicted.