Exodus 7:20-22

20Moses and Aaron obeyed the command of the Lord. Aaron lifted up the stick in front of Pharaoh and his servants. He hit the water in the Nile river with the stick. Then all the water in the river became blood.

21The fish in the river died. The river had such a bad smell that the Egyptians could not drink its water. There was blood in every part of Egypt.

22But the Egyptian magicians used their magic and they did the same thing. So Pharaoh's mind continued to be hard. He still refused to listen to Moses and Aaron. The Lord had said that this would happen, and it did!