Passage 4.5.8
μησὶ δὲ οὐ πολλοῖς ὕστερον Ἀντιόχου τελευτήσαντος Εὐφαὴς ὁ Ἀντιόχου παρέλαβε τὴν ἀρχήν. Λακεδαιμόνιοι δὲ οὔτε κήρυκα ἀποστέλλουσι προεροῦντα Μεσσηνίοις πόλεμον οὔτε προαπειπάμενοι τὴν φιλίαν, κρύφα δὲ καὶ μάλιστα ὡς ἐδύναντο ἐν ἀπορρήτῳ παρασκευασάμενοι, προομνύουσιν ὅρκον μήτε τοῦ πολέμου μῆκος, ἢν μὴ διʼ ὀλίγου κριθῇ, μήτε τὰς συμφοράς, εἰ μεγάλαι πολεμοῦσι γένοιντο, ἀποστρέψειν σφᾶς πρὶν ἢ κτήσαιντο χώραν τὴν Μεσσηνίαν δοριάλωτον.
Not many months later, when Antiochus had died, his son Euphaes took over the rule. The Lacedaemonians sent no herald to declare war openly to the Messenians, nor did they openly renounce friendship beforehand. Instead, they made their preparations secretly and with the utmost concealment. They took an oath, swearing that neither the length of the war, should it not quickly be decided, nor the magnitude of any disasters occurring during it, would deter them until they had conquered Messenian territory by force of arms.