Exodus 7:17-18

7:17 Thus says the Lord: “By this you will know that I am the Lord: I am going to strike the water of the Nile with the staff that is in my hand, and it will be turned into blood. 7:18 Fish in the Nile will die, the Nile will stink, and the Egyptians will be unable to drink water from the Nile.”’”