Exodus 9:10-12

New Revised Standard Version, Anglicised

¹⁰ So they took soot from the kiln, and stood before Pharaoh, and Moses threw it in the air, and it caused festering boils on humans and animals. ¹¹ The magicians could not stand before Moses because of the boils, for the boils afflicted the magicians as well as all the Egyptians. ¹² But the Lord hardened the heart of Pharaoh, and he would not listen to them, just as the Lord had spoken to Moses.