Plato, Letters 334a

δὲ εἰς Σικελίαν, ἐπειδὴ Δίωνα ᾔσθοντο διαβεβλημένον εἰς τοὺς ἐλευθερωθέντας ὑπʼ αὐτοῦ Σικελιώτας ὡς ἐπιβουλεύοντα γενέσθαι τύραννον, οὐ μόνον τὸν ἑταῖρον καὶ ξένον προύδοσαν, ἀλλʼ οἷον τοῦ φόνου αὐτόχειρες ἐγένοντο, ὅπλα ἔχοντες ἐν ταῖς χερσὶν αὐτοὶ τοῖς φονεῦσι παρεστῶτες ἐπίκουροι. καὶ τὸ μὲν αἰσχρὸν καὶ ἀνόσιον οὔτε παρίεμαι ἔγωγε οὔτε τι λέγω—πολλοῖς γὰρ καὶ ἄλλοις ὑμνεῖν ταῦτα ἐπιμελὲς

they perceived that Dion was slanderously charged before the Siceliots whom he had set free with plotting to become tyrant, they not only betrayed their companion and host but became themselves, so to say, the authors of his murder, since they stood beside the murderers, ready to assist, with arms in their hands. For my own part, I neither slur over the shamefulness and sinfulness of their action nor do I dwell on it, since there are many others who make it their care to recount these doings and will continue to do so in time to come.