Passage 4.27.3
οἱ νεανίσκοι δὲ ὡς ἅπαξ ἀνεμίχθησαν, διεξήλαυνον διὰ πάντων παίοντες τοῖς δόρασι, καὶ ἤδη κειμένων πολλῶν ἀποχωροῦσιν ἐς Ἀνδανίαν, καθυβρίσαντες τῶν Διοσκούρων τῇ θυσίᾳ. τοῦτο ἐμοὶ δοκεῖν προήγαγε τοὺς Διοσκούρους ἐς τὸ ἔχθος τὸ Μεσσηνίων· τότε δέ, ὡς ἐδήλου τῷ Ἐπαμινώνδᾳ τὸ ὄνειρον, οὐκ ἦν ἔτι τοῖς Διοσκούροις ἀκούσιος τῶν Μεσσηνίων ἡ κάθοδος.
But when the young men had once mingled with the crowd, they charged through everyone, striking them with spears, and after many had fallen, withdrew to Andania, having thus grievously insulted the festival of the Dioscuri. This event, it seems to me, first stirred the Dioscuri to hatred of the Messenians. Therefore, at the time when Epaminondas was given his dream, the return of the Messenians was no longer against the will of the Dioscuri.