Exodus 7:8-13 MSG

8 Then God spoke to Moses and Aaron. He said,
9 "When Pharaoh speaks to you and says, 'Prove yourselves. Perform a miracle,' then tell Aaron, 'Take your staff and throw it down in front of Pharaoh: It will turn into a snake.'"
10 Moses and Aaron went to Pharaoh and did what God commanded. Aaron threw his staff down in front of Pharaoh and his servants, and it turned into a snake.
11 Pharaoh called in his wise men and sorcerers. The magicians of Egypt did the same thing by their incantations:
12 each man threw down his staff and they all turned into snakes. But then Aaron's staff swallowed their staffs.
13 Yet Pharaoh was as stubborn as ever - he wouldn't listen to them, just as God had said. Strike One: Blood