Exodus 9:6-9

6And the LORD did that thing on the next day, and all the cattle of Egypt died: but of the cattle of the children of Israel died not one. 7And Pharaoh sent, and, behold, there was not one of the cattle of the Israelites dead. And the heart of Pharaoh was hardened, and he did not let the people go.

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.