Jannes and Mambres. The names of the magicians, who in Egypt, resisted Moses, says St. Chrysostom, and though not mentioned in the Scriptures, their names might be known by tradition. (Witham)

Since the Old Testament does not mention these magicians of Pharao, who opposed Moses, it seems probable that St. Paul either learnt their names by a particular revelation, as St. Chrysostom, Theophylactus, and Tirinus think, or by some tradition of the Jews, agreeably to the opinions of Theodoret, Grotius, Estius, &c. Others think he might have found their names in some ancient histories, which have not reached our time; or perhaps from the apocryaphal book of Jannes and Mambres, mentioned by Origen and Ambrosiaster. Certain it is, that in St. Paul’s time the names of these two famous magicians were very well known; thus it is by no means necessary in this instance to have recourse to a particular inspiration. The Orientals say there were many magicians who opposed Moses. Among others, they mention Sabous and Gadous, who came from Thebias; Graath and Mospha, from some other country. They wished, as they inform us, to imitate the miracle by which Moses turned his rod into a serpent, by throwing their canes on the ground, and ropes filled with quicksilver. These ropes began to move a little, one twisting with another, on account of the heat of the earth warmed by the sun. But the rod of Moses in a moment broke them to pieces. (Calmet)

These magicians are called by different names. The Greek has Jannes and Jambres. Some ancient writers, Jannes and Mambres; as St. Cyprian, Optatus, (chap. 7.) Born. &c. The Jews call that Joanne, or Johanna, whom the Greeks name Jannes; and that called by the Jews Jambres, the Greeks name Mambres. The Hebrews would have them to be the sons of Balaam, the soothsayer, and the masters of Moses in the sciences of the Egyptians. (Calmet)