Exodus 7:22 - Joseph Benson’s Commentary on the Old and New Testaments

The magicians did so By God's permission; with their enchantments It seems they performed real miracles, for the text says expressly they did the same as Moses, and probably to their own surprise, as well as that of others, not knowing that any such effect would follow upon their using enchantments. Certainly they were ignorant of the extent of their own power, or rather, what Satan would or could do by them, and by what means these things came to pass, otherwise they would not have disgraced themselves, by making an attempt to bring forth lice, which they could not perform. What they did do served Pharaoh for an excuse not to set his heart to this also. And a poor excuse it was. Could they have turned the river of blood into water again, and by a word have purified those waters which the almighty power of God had rendered corrupt, they would have proved their power and done Pharaoh a signal favour. But the superiority of the miracles of Moses, even in these instances in which they vied with him, was incontestible: and they were compelled to acknowledge that what he did was by the finger of God. “God, by permitting them to succeed thus far in their opposition, rendered their folly more conspicuous: for by suffering them to change the waters into blood, and putting it out of their power to restore them to their former purity; and by permitting them to produce frogs, which they were not able to remove, he only put it in their power to increase those plagues upon themselves and their countrymen at the same time that they demonstrated their own inability.” Bishop Kidder.