Jannes

Jannes is named once in scripture, paired with Jambres as one of the men who "withstood Moses." The Old Testament episode behind that naming sits in the Exodus 7 contest, where Pharaoh's sorcerers match Aaron's sign with witchcraft of their own and are then outdone.

The Egyptian Sorcerer

When Yahweh sent Moses and Aaron to Pharaoh, Aaron cast down his rod before the king "and it became a serpent" (Ex 7:10). Pharaoh's response staffed the contest with his own specialists: "Then Pharaoh also called for the wise men and the sorcerers: and the sacred scholars of Egypt also did in like manner with their witchcraft" (Ex 7:11). Their rods, too, became serpents — "but Aaron's rod swallowed up their rods" (Ex 7:12). The Exodus account names no individual; it gives the class — wise men, sorcerers, sacred scholars — and shows their witchcraft outmatched.

Withstanding Moses

Paul retrieves the episode under personal names. Warning Timothy of false teachers, he writes: "And even as Jannes and Jambres withstood Moses, so do these also withstand the truth; men corrupted in mind, disapproved concerning the faith" (2 Tim 3:8). The pairing fixes Jannes as a paradigm of opposition that mimics the work of God's servant in order to resist it, and is finally exposed as "corrupted in mind, disapproved concerning the faith."