Exodus 7:23

21The fish that were in the river died. The river became foul. The Egyptians couldn’t drink water from the river. The blood was throughout all the land of Egypt.

22The magicians of Egypt did the same thing with their enchantments. So Pharaoh’s heart was hardened, and he didn’t listen to them, as the LORD had spoken.

23Pharaoh turned and went into his house, and he didn’t even take this to heart.

24All the Egyptians dug around the river for water to drink; for they couldn’t drink the river water.

25Seven days were fulfilled, after the LORD had struck the river.