Jerome. Lives of Illustrious Men 59
59 Gaius PL 23, 669
Gaius, bishop of Rome, in the time of Zephyrinus, that is, in the reign of Antoninus, the son of Severus, delivered a very notable disputation Against Proculus, the follower of Montanus, convicting him of temerity in his defence of the new prophecy, and in the same volume also enumerating only thirteen epistles of Paul, says that the fourteenth, which is now called, To the Hebrews, is not by him, and is not considered among the Romans to the present day as being by the apostle Paul.
899 Gaius, sub Zephyrino Romanae urbis episcopo, id est sub Antonino Severi filio, disputationem adversum Proculum, Montani sectatorem, valde insignem habuit, arguens eum temeritatis, super Nova Prophetia defendenda, et in eodem volumine Epistolas quoque Pauli, tredecim tantum enumerans; decimam quartam quae fertur ad Hebraeos, dicit non ejus esse, sed et apud Romanos usque hodie quasi Pauli apostoli non habetur.
900 Γαΐος ἐπὶ Ζεφυρίνου Ῥώμης ἐπισκόπου, τοῦτ' ἔστιν, ἐπὶ Ἀντωνίνου υἱοῦ Σεβήρου, διάλεξιν κατὰ Προκούλου σπουδαστοῦ Μοντανοῦ, σφόδρα μεγίστην ἔσχεν, εὐθύνων αὐτὸν προπετείας, τῆς καινῆς Προφητείας, ἐν αὐτῷ τῷ τεύχει τρισκαίδεκα Ἐπιστολὰς μόνας Παύλου ἀπαριθμούμενος· τὴν γὰρ πρὸς Ἑβραίους λέγει μὴ εἶναι αὐτοῦ, ἀλλὰ καὶ παρὰ τοῖς Ῥωμαίοις ἄχρι τοῦ παρόντος Παύλου ἀποστόλου νομίζεται μὴ εἶναι.