Exodus 9:9-13

Then it will become fine dust over all the land of Egypt, and will turn into boils breaking out with sores on every person and animal through all the land of Egypt.”

So they took soot from a kiln, and stood before Pharaoh; and Moses tossed it toward the sky, and it became boils breaking out with sores on every person and animal.

The soothsayer priests could not stand before Moses because of the boils, for the boils were on the soothsayer priests as well as on all the Egyptians.

But the Lord hardened Pharaoh’s heart, and he did not listen to them, just as the Lord had spoken to Moses.

Then the Lord said to Moses, “Rise up early in the morning and stand before Pharaoh and say to him, ‘This is what the Lord, the God of the Hebrews says: “Let My people go, so that they may serve Me.