Exodus 4:9; Exodus 29:12

Exodus 4:9

9 "But if they will not believe even these two signs or heed 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 will become blood on the dry ground."

Exodus 29:12

12 "You shall take some of the blood of the bull and put it on the horns of the altar with your finger; and you shall pour out all the blood at the base of the altar.