Exodus 7:20-22 New Revised Standard Version, Anglicised Catholic Edition (NRSVACE)
20 Moses and Aaron did just as the Lord commanded. In the sight of Pharaoh and of his officials he lifted up the staff and struck the water in the river, and all the water in the river was turned into blood, 21 and the fish in the river died. The river stank so that the Egyptians could not drink its water, and there was blood throughout the whole land of Egypt. 22 But the magicians of Egypt did the same by their secret arts; so Pharaoh’s heart remained hardened, and he would not listen to them, as the Lord had said.