Pseudo Jonathan Exodus 1:15
15 And Pharaoh said that while he slept, he saw in his dream that all the land of Egypt was placed on one balance of a weighing scale, and a lamb, the young of a ewe, on the other balance of the weighing scale; and the balance of the weighing scale on which the lamb was placed weighed down. Immediately he sent and summoned all the magicians of Egypt and told them his dream. Immediately Jannes and Jambres, the chief magicians, opened their mouths and said to Pharaoh: 'A son is to be born in the assembly of Israel, through whom all the land of Egypt is destined to be destroyed.'
2 Timothy 3:8
6 For some of these insinuate themselves into households and captivate weak women who are overwhelmed with sins and led along by various passions. 7 Such women are always seeking instruction, yet never able to arrive at a knowledge of the truth. 8 And just as Jannes and Jambres opposed Moses, so these people—who have warped minds and are disqualified in the faith—also oppose the truth. 9 But they will not go much further, for their foolishness will be obvious to everyone, just like it was with Jannes and Jambres.
Notes and References
"... My pastor was not aware that his casual comment was extrabiblical, an ancient tradition designed to explain a puzzling element in the biblical story. This phenomenon is sometimes referred to as the “interpreted Bible.” What earnest Bible readers think the Bible says is sometimes a merging of what is there in black and white and how one’s faith tradition has come to understand it. And that merger is often seamless, so much so that most readers are not even aware of it. Biblical writers were not immune to this phenomenon. For example, in 2 Timothy 3:8 we see a casual reference to the magicians in Pharaoh’s court of Moses’s day as Jannes and Jambres. Where did these names come from? No names are given in the Old Testament. Nor are they the product of special revelation, for they simply come up in the flow of the argument with no fanfare, no indication that the writer is now privy to some special or long-lost (and irrelevant) piece of information. If we want to understand the source of this information, it is in the interpretive traditions of his Second Temple world. The name Jannes is found among the Dead Sea Scrolls (Damascus Covenant 5.17–19), and both names are found in a targum (Targum Pseudo-Jonathan to Exodus 1:15). During the Second Temple period it was common to “concretize” biblical episodes by giving names to otherwise anonymous biblical figures, and “Jannes and Jambres” is an example of that. These names then became part of a larger cultural conviction about the biblical story (like the names of the three wise men), and 2 Timothy 3:8 is an instance of that process ..."
Enns, Peter The Evolution of Adam: What the Bible Does and Doesn’t Say about Human Origins (pp. 114-115) Brazos Press, 2012