Exodus 9:8 – 12
New International Version (NIV)
The Plague of Boils
8 Then the LORD said to Moses and Aaron, “Take handfuls of soot from a furnace and have Moses toss it into the air in the presence of Pharaoh. 9 It will become fine dust over the whole land of Egypt, and festering boils will break out on people and animals throughout the land.”
10 So they took soot from a furnace and stood before Pharaoh. Moses tossed it into the air, and festering boils broke out on people and animals. 11 The magicians could not stand before Moses because of the boils that were on them and on all the Egyptians. 12 But the LORD hardened Pharaoh's heart and he would not listen to Moses and Aaron, just as the LORD had said to Moses.
From BibleGateway.com: http://www.biblegateway.com/passage/?search=Exodus 9:8-12&version=NIV