Exodus 7:21

¹⁹And the Lord said to Moses, Say to thy brother Aaron, Take thy rod in thy hand, and stretch forth thy hand over the waters of Egypt, and over their rivers, and over their canals, and over their ponds, and over all their standing water, and it shall become blood: and there was blood in all the land of Egypt, both in vessels of wood and of stone.

²⁰And Moses and Aaron did so, as the Lord commanded them; and Aaron having lifted up his hand with his rod, smote the water in the river before Pharaoh, and before his servants, and changed all the water in the river into blood.

— Exodus 7:21 —

²²And the charmers also of the Egyptians did so with their sorceries; and the heart of Pharaoh was hardened, and he did not hearken to them, even as the Lord said.

²³And Pharaoh turned and entered into his house, nor did he fix his attention even on this thing.