Exodus 7:22-25

But the magicians of Egypt did the same thing with their incantations. Still Pharaoh remained stubborn. He wouldn’t listen to them as GOD had said. He spun around and went home, never giving it a second thought. But all the Egyptians had to dig inland from the river for water because they couldn’t drink the Nile water. Seven days went by after GOD had struck the Nile.