Exodus 7:22-26

But the soothsayer priests of Egypt did the same with their secret arts; and Pharaoh’s heart was hardened, and he did not listen to them, just as the Lord had said.

Then Pharaoh turned and went into his house with no concern even for this.

So all the Egyptians dug around the Nile for water to drink, because they could not drink from the water of the Nile.

Seven days passed after the Lord had struck the Nile.