Exodus 7:14-18

Then the LORD said to Moses, “Pharaoh’s heart is stubborn, and he still refuses to let the people go. So go to Pharaoh in the morning as he goes down to the river. Stand on the bank of the Nile and meet him there. Be sure to take along the staff that turned into a snake. Then announce to him, ‘The LORD, the God of the Hebrews, has sent me to tell you, “Let my people go, so they can worship me in the wilderness.” Until now, you have refused to listen to him. So this is what the LORD says: “I will show you that I am the LORD.” Look! I will strike the water of the Nile with this staff in my hand, and the river will turn to blood. The fish in it will die, and the river will stink. The Egyptians will not be able to drink any water from the Nile.’”