Passage 3.8.3
ἐπὶ δὲ Ἄγιδος τοῦ Ἀρχιδάμου βασιλεύοντος Λακεδαιμονίοις ἄλλα τε ἐγένετο ἐς Ἠλείους ἐγκλήματα καὶ τοῦ ἀγῶνος τοῦ Ὀλυμπικοῦ καὶ ἱεροῦ τοῦ Ὀλυμπίασιν ὑπʼ αὐτῶν εἰργόμενοι μάλιστα ἤχθοντο. ἀποστέλλουσιν οὖν κήρυκα ἐπίταγμα φέροντα Ἠλείοις Λεπρεάτας τε αὐτονόμους ἀφιέναι καὶ ὅσοι τῶν περιοίκων ἄλλοι σφίσιν ἦσαν ὑπήκοοι. ἀποκριναμένων δὲ Ἠλείων ὡς ἐπειδὰν τὰς περιοικίδας τῆς Σπάρτης πόλεις ἴδωσιν ἐλευθέρας, οὐδὲ αὐτοὶ μελλήσουσιν ἔτι ἀφιέναι τὰς ἑαυτῶν, οὕτω Λακεδαιμόνιοι καὶ ὁ βασιλεὺς Ἆγις ἐσβάλλουσιν ἐς τὴν Ἠλείαν.
During the reign of Agis, son of Archidamus, king of the Lacedaemonians, various charges arose against the Eleans, but the Spartans were especially angered at being excluded by them from the Olympic Games and from the sanctuary at Olympia. They therefore dispatched a herald to Elis, bearing orders to release Lepreum into autonomy, as well as any neighboring communities still subject to Elis. When the Eleans replied that as soon as they saw Sparta granting freedom to its own subject cities, they themselves would promptly release theirs, the Lacedaemonians and King Agis proceeded to invade Elis.