Plato, Laws 834c

μονίπποις δὲ ἆθλα τιθέντες, πώλοις τε ἀβόλοις καὶ τελείων τε καὶ ἀβόλων τοῖς μέσοις καὶ αὐτοῖς δὴ τοῖς τέλος ἔχουσι, κατὰ φύσιν τῆς χώρας ἂν τὴν ἱππικὴν παιδιὰν ἀποδιδοῖμεν. ἔστω δὴ τούτων τε αὐτῶν κατὰ νόμον ἅμιλλά τε καὶ φιλονικία, φυλάρχοις τε καὶ ἱππάρχοις δεδομένη κοινὴ κρίσις ἁπάντων τῶν τε δρόμων αὐτῶν καὶ τῶν καταβαινόντων μεθʼ ὅπλων· ψιλοῖς δὲ ὅπλων οὔτʼ ἐν τοῖς γυμνικοῖς οὔτε ἐνταῦθα

both for young colts, and for three-year-olds, and for those of full age—we shall be adapting the sport of horse-racing to the character of the country. Of these horsemen there shall be established by law a competitive contest, and the phylarchs and hipparchs shall act as public judges both of all the races and of the armed competitors. For unarmed competitors we should be wrong in establishing prizes, either here or in the gymnastic sports.