Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments. For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods. Exodus 7:11,12
"Then Pharaoh also called.... The impiety of the tyrant, which had before lain hid in the recesses of his heart, now breaks forth; when he does not hesitate to enter into the lists with God.
Thus the wickedness of Pharaoh blinded his eyes, that, seeing the light, he saw it not; but, though convinced, still he sought for darkness to hide the sight of the light from him.
--Q--Are we surprised at Pharaoh calling for the magicians, in order to repel from himself his sense of God’s power?
For they cast down every man... The number of the magicians is not expressed; and although Paul names two, Jannes and Jambres, it is probable that they were not the only ones, but the chief, and, as it were, the ringleaders....The admonition of Paul is more to the purpose, that “as Jannes and Jambres withstood Moses,” so also there should always be false teachers... It is an awful fact that the reins were so given to these magicians, that they contended with Moses in almost an equal contest.
Nor must the mark of distinction be overlooked, that the rod of Moses swallowed up the rods of the magicians.
--Q--How then was it that Pharaoh did not perceive Moses to be victorious? --Q-- how was it that he rather turned aside to his own impostors?"
Calvin