Exodus 7:17

17 Thus says the Lord, "By this you shall know that I am the Lord." See, with the staff that is in my hand I will strike the water that is in the Nile, and it shall be turned to blood.

Exodus 7:17 In-Context

15 Go to Pharaoh in the morning, as he is going out to the water; stand by at the river bank to meet him, and take in your hand the staff that was turned into a snake.
16 Say to him, "The Lord, the God of the Hebrews, sent me to you to say, "Let my people go, so that they may worship me in the wilderness." But until now you have not listened.
17 Thus says the Lord, "By this you shall know that I am the Lord." See, with the staff that is in my hand I will strike the water that is in the Nile, and it shall be turned to blood.
18 The fish in the river shall die, the river itself shall stink, and the Egyptians shall be unable to drink water from the Nile.' "
19 The Lord said to Moses, "Say to Aaron, "Take your staff and stretch out your hand over the waters of Egypt—over its rivers, its canals, and its ponds, and all its pools of water—so that they may become blood; and there shall be blood throughout the whole land of Egypt, even in vessels of wood and in vessels of stone.' "
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.