Observe here, concerning the plague of boils and blains,

I.When they were not wrought upon by the death of their cattle, God sent a plague that seized their own bodies, and touched them to the quick. If less judgments do not do their work, God will send greater. Let us therefore humble ourselves under the mighty hand of God, and go forth to meet him in the way of his judgments, that his anger may be turned away from us.

II.The signal by which this plague was summoned was the sprinkling of warm ashes from the furnace, towards heaven (Exo 9:8, Exo 9:10), which was to signify the heating of the air with such an infection as should produce in the bodies of the Egyptians sore boils, which would be both noisome and painful. Immediately upon the scattering of the ashes, a scalding dew came down out of the air, which blistered wherever it fell. Note, 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 as much a terror to them as ever their task-masters had been to the Israelites.

III.The plague itself was very grievous - a common eruption would be so, especially to the nice and delicate, but these eruptions were inflammations, like Job's. This is afterwards called the botch of Egypt (Deu 28:27), as if it were some new disease, never heard of before, and known ever after by that name, Note, Sores in the body are to be looked upon as the punishments of sin, and to be hearkened to as calls to repentance.

IV.The magicians themselves were struck with these boils, Exo 9:11. 1. Thus they were punished, (1.) For helping to harden Pharaoh's heart, as Elymas for seeking to ;pervert the right ways of the Lord; God will severely reckon with those that strengthen the hands of the wicked in their wickedness. (2.) For pretending to imitate the former plagues, and making themselves and Pharaoh sport with them. Those that would produce lice shall, against their wills, produce boils. Note, It is ill jesting with God's judgments, and more dangerous than playing with fire. Be you not mockers, lest your bands be made strong. 2. Thus they were shamed in the presence of their admirers. How weak were their enchantments, which could not so much as secure themselves! The devil can give no protection to those that are in confederacy with him. 3. Thus they were driven from the field. Their power was restrained before (Exo 8:18), but they continued to confront Moses, and confirm Pharaoh in his unbelief, till now, at length, they were forced to retreat, and could not stand before Moses, to which the apostle refers (Ti2 3:9) when he says that their folly was made manifest unto all men.

V.Pharaoh continued obstinate, for now the Lord hardened his heart, Exo 9:12. Before, he had hardened his own heart, and resisted the grace of God; and now God justly gave him up to his own heart's lusts, to a reprobate mind, and strong delusions, permitting Satan to blind and harden him, and ordering every thing, henceforward, so as to make him more and more obstinate. Note, Wilful hardness is commonly punished with judicial hardness. If men shut their eyes against the light, it is just with God to close their eyes. Let us dread this as the sorest judgment a man can be under on this side hell.

The boil was upon the magicians - They could not produce a similar malady by throwing ashes in the air; and they could neither remove the plague from the people, nor from their own tormented flesh. Whether they perished in this plague we know not, but they are no more mentioned. If they were not destroyed by this awful judgment, they at least left the field, and no longer contended with these messengers of God. The triumph of God's power was now complete, and both the Hebrews and the Egyptians must see that there was neither might, nor wisdom, nor counsel against the Lord; and that, as universal nature acknowledged his power, devils and men must fail before him.

And the Lord hardened the heart of Pharaoh,.... He having often, and so long hardened his own heart, God gave him up to judicial hardness of heart, to his own corruptions, the temptations of Satan, and the lying magicians about him, to make an ill use of everything that offered to him, and put a wrong construction on all that befell him, so that whatever was said to him, or inflicted on him, made no impression to any purpose:

and he hearkened not unto them; to Moses and Aaron, and to the Lord by them:

as the Lord had spoken to Moses; both that he would harden his heart, and he should not hearken to them; all this was no other than what the Lord had said should be, Exo 4:21.

Moses took ashes from the furnace--Hebrew, "brick-kiln." The magicians, being sufferers in their own persons, could do nothing, though they had been called; and as the brick-kiln was one of the principal instruments of oppression to the Israelites [Deu 4:20; Kg1 8:51; Jer 11:4], it was now converted into a means of chastisement to the Egyptians, who were made to read their sin in their punishment.