Exodus 9:7-8

9:7 Pharaoh sent representatives to investigate, and indeed, not even one of the livestock of Israel had died. But Pharaoh’s heart remained hard, and he did not release the people.

The Sixth Blow: Boils

9:8 Then the Lord said to Moses and Aaron, “Take handfuls of soot from a furnace, and have Moses throw it into the air while Pharaoh is watching.