Exodus 9:9-11

9:9 It will become fine dust over the whole land of Egypt and will cause boils to break out and fester on both people and animals in all the land of Egypt.” 9:10 So they took soot from a furnace and stood before Pharaoh, Moses threw it into the air, and it caused festering boils to break out on both people and animals.

9:11 The magicians could not stand before Moses because of the boils, for boils were on the magicians and on all the Egyptians.