Exodus 9:8-10

8Then the Lord said to Moses and Aaron, “Take handfuls of furnace soot, and Moses is to throw it toward heaven in the sight of Pharaoh.

9It will become fine dust over the entire land of Egypt. It will become festering boils on people and animals throughout the land of Egypt.”

10So they took furnace soot and stood before Pharaoh. Moses threw it toward heaven, and it became festering boils on people and animals.