Exodus 7:10-15

7:10 When Moses and Aaron went to Pharaoh, they did so, just as the Lord had commanded them – Aaron threw down his staff before Pharaoh and his servants and it became a snake. 7:11 Then Pharaoh also summoned wise men and sorcerers, and the magicians of Egypt by their secret arts did the same thing. 7:12 Each man threw down his staff, and the staffs became snakes. But Aaron’s staff swallowed up their staffs. 7:13 Yet Pharaoh’s heart became hard, and he did not listen to them, just as the Lord had predicted.

The First Blow: Water to Blood

7:14 The Lord said to Moses, “Pharaoh’s heart is hard; he refuses to release the people. 7:15 Go to Pharaoh in the morning when he goes out to the water. Position yourself to meet him by the edge of the Nile, and take in your hand the staff that was turned into a snake.