Passage 3.11.8
τέταρτον δὲ ἠγωνίσατο πρὸς τοὺς ἐξ ἰσθμοῦ ἐς Ἰθώμην ἀποστάντας ἀπὸ τῶν εἱλώτων· ἀπέστησαν δὲ οὐχ ἅπαντες οἱ εἵλωτες, ἀλλὰ τὸ Μεσσηνιακὸν ἀπὸ τῶν ἀρχαίων εἱλώτων ἀποσχισθέντες· καί μοι καὶ τάδε ὁ λόγος αὐτίκα ἐπέξεισι. τότε δὲ οἱ Λακεδαιμόνιοι τοὺς ἀποστάντας ἀπελθεῖν ὑποσπόνδους εἴασαν Τισαμενῷ καὶ τῷ ἐν Δελφοῖς χρηστηρίῳ πειθόμενοι· τελευταῖον δὲ ὁ Τισαμενὸς ἐμαντεύσατο ἐν Τανάγρᾳ σφίσι πρὸς Ἀργείους καὶ Ἀθηναίους γινομένης συμβολῆς.
Fourthly, they fought against those helots who revolted from the Isthmus to Ithome. Not all the helots revolted, however, but only the descendants of the ancient Messenians, who split away from the original helot group. The account concerning this event I shall presently discuss further. On that occasion the Lacedaemonians permitted the revolters to leave under a truce, following the advice of Tisamenus and the oracle at Delphi. Tisamenus later prophesied for them at Tanagra when they were preparing for battle against the Argives and Athenians.