Exodus 9:11
And the magicians could not stand before Moses because of the boils; for the boil was upon the magicians, and upon all the Egyptians. And the magicians could not stand before Moses because of the boils; for the boil was upon the magicians, and upon all the Egyptians.
By divine command ashes from the furnace were taken and sprinkled toward heaven, becoming a boil breaking forth with blains upon both man and beast. What had been a rite intended to avert evil was turned into a judgment, and from it no king, priest, or ordinary person escaped.
The plague followed the murrain upon Egyptian cattle, from which the cattle of the Hebrews had been spared. It came at a time announced beforehand, so that it could not be said to have happened by chance.
The boil was upon the magicians and upon all the Egyptians, and because of the grievous affliction the magicians could not stand before Moses and Aaron. They who had stood to oppose and contend were now unable to stand, and unable to contend against the God of Israel.
With all their magic, enchantments, and supposed power, they could not by any means shield or protect even their own bodies and persons from the plague. They could not save themselves from the plagues but felt God's wrath themselves, struck with boils like all the Egyptians.
They had worked not by human science and skill alone but by the power of Satan counterfeiting God's work through Moses, while Moses' signs came from God and not from human skill. By this plague God's controlling power cut off and stopped the channel through which Satan had worked through them. God would not suffer Satan to proceed further in imitation, so they could no more imitate Moses and Aaron, nor oppose them, nor contend against the God of Israel.
Their suffering and inability to imitate demonstrated that God's power surpassed Satan's power working through them, and that God's work was superior. It let the Egyptians see how useless and foolish it was to put trust in their boasted power. It exposed the powerlessness of Egypt's idols and affirmed Jehovah's supremacy, showing that the whole earth is under the command of the God of the Hebrews, whom thunder, hail, and storm obey.
After this the Lord hardened Pharaoh's heart and he hearkened not, as the Lord had spoken unto Moses.