exodus 7:11 Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments. - Free Bible Online

      11. Then Pharaoh also called the wise men and the sorcerers, &c.--His object in calling them was to ascertain whether this doing of Aaron's was really a work of divine power or merely a feat of magical art. The magicians of Egypt in modern times have been long celebrated adepts in charming serpents, and particularly by pressing the nape of the neck, they throw them into a kind of catalepsy, which renders them stiff and immovable--thus seeming to change them into a rod. They conceal the serpent about their persons, and by acts of legerdemain produce it from their dress, stiff and straight as a rod. Just the same trick was played off by their ancient predecessors, the most renowned of whom, Jannes and Jambres (2Ti 3:8), were called in on this occasion. They had time after the summons to make suitable preparations--and so it appears they succeeded by their "enchantments" in practising an illusion on the senses.

JFB.