Exodus 9:8-12

8 And the Lord said to Moses and Aaron, “Take handfuls of soot from the kiln, and let Moses throw them in the air in the sight of Pharaoh. 9 It shall become fine dust over all the land of Egypt, and become boils breaking out in sores on man and beast throughout all the land of Egypt.” 10 So they took soot from the kiln and stood before Pharaoh. And Moses threw it in the air, and it became boils breaking out in sores on man and beast. 11 And the magicians could not stand before Moses because of the boils, for the boils came upon the magicians and upon all the Egyptians. 12 But the Lord hardened the heart of Pharaoh, and he did not listen to them, as the Lord had spoken to Moses.

Remember, there are dark spiritual powers at work in Egypt, and Pharaoh’s men can work with them and perform some wonders, but as the plagues continue and intensify, even Pharaoh’s sorcerers become victims—here they are covered with boils.

Once again, the Lord is trying to teach them to recognize His rightful authority over all things, and to turn aside from their evil ways. The magicians seem to begin to recognize God’s power, but Pharaoh still refuses.