Exodus 9:12 KJV

10And they took ashes of the furnace, and stood before Pharaoh; and Moses sprinkled it up toward heaven; and it became a boil breaking forth with blains 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 unto them; as the LORD had spoken unto Moses.

13And the LORD said unto Moses, Rise up early in the morning, and stand before Pharaoh, and say unto him, Thus saith the LORD God of the Hebrews, Let my people go, that they may serve me.

14For I will at this time send all my plagues upon thine heart, and upon thy servants, and upon thy people; that thou mayest know that there is none like me in all the earth.