8 So the Lord said to Moses and Aaron, "Take for yourselves handfuls of ashes from a furnace, and let Moses scatter it toward the heavens in the sight of Pharaoh. 9 And it will become fine dust in all the land of Egypt, and it will cause boils that break out in sores on man and beast throughout all the land of Egypt." 10 Then they took ashes from the furnace and stood before Pharaoh, and Moses scattered them toward heaven. And they caused boils that break out in sores on man and beast. 11 And the magicians could not stand before Moses because of the boils, for the boils were on the magicians and on all the Egyptians. 12 But the Lord hardened the heart of Pharaoh; and he did not heed them, just as the Lord had spoken to Moses.
Matthew Henry's Commentary on Exodus 9:8-12
Commentary on Exodus 9:8-12
(Read Exodus 9:8-12)
When the Egyptians were not wrought upon by the death of their cattle, God sent a plague that seized their own bodies. If lesser judgments do not work, God will send greater. Sometimes God shows men their sin in their punishment. They had oppressed Israel in the furnaces, and now the ashes of the furnace are made a terror to them. The plague itself was very grievous. The magicians themselves were struck with these boils. Their power was restrained before; but they continued to withstand Moses, and to confirm Pharaoh in his unbelief, till they were forced to give way. Pharaoh continued obstinate. He had hardened his own heart, and now God justly gave him up to his own heart's lusts, permitting Satan to blind and harden him. If men shut their eyes against the light, it is just with God to close their eyes. This is the sorest judgment a man can be under out of hell.