Exodus 7:22-24 NIV

[22] But the Egyptian magicians did the same things by their secret arts, and Pharaoh’s heart became hard; he would not listen to Moses and Aaron, just as the LORD had said. [23] Instead, he turned and went into his palace, and did not take even this to heart. [24] And all the Egyptians dug along the Nile to get drinking water, because they could not drink the water of the river.