Exodus 7:20-22

Complete Jewish Bible

²⁰ Moshe and Aharon did exactly what Adonai had ordered. He raised the staff and, in the sight of Pharaoh and his servants, struck the water in the river; and all the water in the river was turned into blood. ²¹ The fish in the river died, and the river stank so badly that the Egyptians couldn’t drink its water. There was blood throughout all the land of Egypt.

²² But the magicians of Egypt did the same with their secret arts, so that Pharaoh was made hardhearted and didn’t listen to them, as Adonai had said would happen.