Exodus 9:10-14

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.

For this time I am going to send all My plagues on you and your servants and your people, so that you may know that there is no one like Me in all the earth.