Exodus 9:6-9

6And the Lord did this thing the next day, and all [kinds of] the livestock of Egypt died; but of the livestock of the Israelites, not one died.

7Then Pharaoh sent [men to investigate], and not even one of the livestock of the Israelites had died. But the heart of Pharaoh was hardened [and his mind was firmly set], and he did not let the people go.

8Then the Lord said to Moses and Aaron, “Take handfuls of soot from the brick kiln, and let Moses throw it toward the sky in the sight of Pharaoh.

9It will become fine dust over the entire land of Egypt, and it will become boils breaking out in sores on man and animal in all the land [occupied by the Egyptians].”