Exodus 9:9-11

9And it shall become fine dust over all the land of Egypt, and shall become boils on man and on cattle, breaking out [with] blisters, throughout the land of Egypt.

10And they took ashes of the furnace, and stood before Pharaoh; and Moses sprinkled it toward the heavens; and it became boils [with] blisters breaking out on man and on cattle.

11And the scribes could not stand before Moses because of the boils; for the boils were on the scribes, and on all the Egyptians.