Passage 4.17.2
τρίτῳ δὲ ἔτει τοῦ πολέμου μελλούσης γίνεσθαι συμβολῆς ἐπὶ τῇ καλουμένῃ Μεγάλῃ τάφρῳ καὶ Μεσσηνίοις Ἀρκάδων βεβοηθηκότων ἀπὸ πασῶν τῶν πόλεων, Ἀριστοκράτην τὸν Ἱκέτα Τραπεζούντιον, βασιλέα τῶν Ἀρκάδων καὶ στρατηγὸν ὄντα ἐν τῷ τότε, διαφθείρουσιν οἱ Λακεδαιμόνιοι χρήμασι. πρῶτοι γὰρ ὧν ἴσμεν Λακεδαιμόνιοι πολεμίῳ ἀνδρὶ δῶρα ἔδοσαν, καὶ ὤνιον πρῶτοι κατεστήσαντο εἶναι τὸ κράτος τὸ ἐν τοῖς ὅπλοις·
In the third year of the war, when battle was about to occur at the place called the Great Trench, the Arcadians from all their cities had come to help the Messenians. Aristocrates son of Hicetas of Trapezus, who was king of the Arcadians and at this time their general, was bribed with money by the Lacedaemonians, who thus corrupted him. The Lacedaemonians were, as far as we know, the first to give gifts to a hostile leader, and they were the first to establish the practice of purchasing victory in war.