Exodus 9:8-12

8And the LORD said to Moses and to Aaron, Take to you handfuls of ashes of the furnace, and let Moses sprinkle it toward heaven in the sight of Pharaoh. 9And it shall become small dust in all the land of Egypt, and shall be a boil breaking forth with sores upon man, and upon beast, throughout all the land of Egypt. 10And they took ashes of the furnace, and stood before Pharaoh; and Moses sprinkled it toward heaven; and it became a boil breaking forth with sores upon man, and upon beast. 11And the magicians could not stand before Moses because of the boils; for the boil was upon the magicians, and upon all the Egyptians. 12And the LORD hardened the heart of Pharaoh, and he hearkened not to them; as the LORD had spoken to Moses.