Exodus 9:9-11

9It will become fine dust over the whole land of Egypt, and festering boils will break out on people and animals throughout the land.” 10So they took soot from a furnace and stood before Pharaoh. Moses tossed it into the air, and festering boils broke out on people and animals. 11The magicians could not stand before Moses because of the boils that were on them and on all the Egyptians.