Exodus 7:17-22

Thus says the LORD, “By this you shall know that I am the LORD: behold, I will strike the water that is in the Nile with the staff that is in my hand, and it will be turned to blood. The fish that are in the Nile will die, and the Nile will become foul, and the Egyptians will find difficulty in drinking water from the Nile.” ’ ” Then the LORD said to Moses, “Say to Aaron, ‘Take your staff and stretch out your hand over the waters of Egypt, over their rivers, over their streams, and over their pools, and over all their reservoirs of water, that they may become blood; and there will be blood throughout all the land of Egypt, both in vessels of wood and in vessels of stone.’ ” So Moses and Aaron did even as the LORD had commanded. And he lifted up the staff and struck the water that was in the Nile, in the sight of Pharaoh and in the sight of his servants, and all the water that was in the Nile was turned to blood. The fish that were in the Nile died, and the Nile became foul, so that the Egyptians could not drink water from the Nile. And the blood was through all the land of Egypt. But the magicians of Egypt did the same with their secret arts; and Pharaoh’s heart was hardened, and he did not listen to them, as the LORD had said.