Exodus 4:8-9

8“So if they will not believe you nor 1pay attention to the 2evidence of the first 3sign, they may believe the 4evidence of the last 5sign. 9But if they will not believe even these two 6signs nor pay attention to what you say, then you shall take some water from the Nile and pour it on the dry ground; and the water which you take from the Nile 7will turn into blood on the dry ground.”