Exodus 7:19-25

And Jehovah said unto Moses, Say unto Aaron, Take thy rod, and stretch out thy hand over the waters of Egypt, over their rivers, over their streams, and over their pools, and over all their ponds of water, that they may become blood; and there shall be blood throughout all the land of Egypt, both in vessels of wood and in vessels of stone. And Moses and Aaron did so, as Jehovah commanded; and he lifted up the rod, and smote the waters that were in the river, in the sight of Pharaoh, and in the sight of his servants; and all the waters that were in the river were turned to blood. And the fish that were in the river died; and the river became foul, and the Egyptians could not drink water from the river; and the blood was throughout all the land of Egypt. And the magicians of Egypt did in like manner with their enchantments: and Pharaoh’s heart was hardened, and he hearkened not unto them; as Jehovah had spoken. And Pharaoh turned and went into his house, neither did he lay even this to heart. And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river. And seven days were fulfilled, after that Jehovah had smitten the river.