Passage 9.13.8
τῷ δὲ Ἐπαμινώνδᾳ καὶ ἐς ἄλλους Βοιωτῶν ὕποπτα ἦν, ἐς δὲ τοὺς Θεσπιεῖς καὶ περισσότερον· δείσας οὖν μὴ σφᾶς παρὰ τὸ ἔργον προδῶσιν, ἀποχώρησιν παρεῖχεν ἀπὸ στρατοπέδου τοῖς ἐθέλουσιν οἴκαδε· καὶ οἱ Θεσπιεῖς τε ἀπαλλάσσονται πανδημεὶ καὶ εἴ τισιν ἄλλοις Βοιωτῶν ὑπῆν δύσνοια ἐς τοὺς Θηβαίους.
Epaminondas had suspected the loyalty of other Boeotians as well, but his suspicion was even greater against the Thespians. Therefore, fearing they might betray him in the midst of action, he gave leave to depart openly from the camp to whoever wished to go home. As a consequence, the Thespians departed altogether, along with any other Boeotians who harbored disaffection toward the Thebans.