Exodus 9:8-10

8So the Lord said to Moses and Aaron, “Take for yourselves handfuls of ashes from a furnace, and let Moses scatter it toward the heavens in the sight of Pharaoh.

9And it will become fine dust in all the land of Egypt, and it will cause boils that break out in sores on man and beast throughout all the land of Egypt.”

10Then they took ashes from the furnace and stood before Pharaoh, and Moses scattered them toward heaven. And they caused boils that break out in sores on man and beast.