Exodus 4:8-9
Exodus 4:8-9 ESV
“If they will not believe you,” God said, “or listen to the first sign, they may believe the latter sign. If they will not believe even these two signs or listen to your voice, you shall take some water from the Nile and pour it on the dry ground, and the water that you shall take from the Nile will become blood on the dry ground.”