Exodus 7:19-22

19And Jehovah said to Moses, Say unto Aaron, Take thy staff, and stretch out thy hand upon the waters of the Egyptians — upon their streams, upon their rivers, and upon their ponds, and upon all their reservoirs of water, that they may become blood; and there shall be blood throughout the land of Egypt, both in [vessels of] wood and in [vessels of] stone.

20And Moses and Aaron did so, as Jehovah had commanded; and he lifted up the staff, and smote the waters that were in the river before the eyes of Pharaoh, and before the eyes of his bondmen; and all the waters that were in the river were turned into blood.

21And the fish that was in the river died; and the river stank, and the Egyptians could not drink the water of the river; and the blood was throughout the land of Egypt.

22And the scribes of Egypt did so with their sorceries; and Pharaoh's heart was stubborn, neither did he hearken to them, as Jehovah had said.