EXO 7:17

17 [So now] Yahweh says this: “This is the way you will know that I, Yahweh, [have the power to do what I say that I will do]. Watch this: I am going to strike the water that is in the Nile [River] with the stick that is in my hand. [When I do that], the water will become blood (OR, [red like] blood [MTY]).