Exodus 9:10-12

New Century Version

¹⁰ So Moses and Aaron took ashes from a furnace and went and stood before the king. Moses threw ashes into the air, which caused boils to break out and become sores on people and animals. ¹¹ The magicians could not stand before Moses, because all the Egyptians had boils, even the magicians. ¹² But the Lord made the king stubborn, so he refused to listen to Moses and Aaron, just as the Lord had said.