Passage 4.28.3
Ἀλεξάνδρου δὲ ἀποθανόντος καὶ τῶν Ἑλλήνων πόλεμον δεύτερον τότε ἀνῃρημένων πρὸς Μακεδόνας, μετέσχον καὶ οἱ Μεσσήνιοι τοῦ πολέμου, καθὰ καὶ πρότερον ἐδήλωσα ἐν τῇ Ἀτθίδι συγγραφῇ. Γαλάταις δὲ μεθʼ Ἑλλήνων οὐκ ἐμαχέσαντο, Κλεωνύμου καὶ Λακεδαιμονίων σπείσασθαι σπονδάς σφισιν οὐ θελησάντων.
After Alexander's death, when the Greeks undertook a second war against the Macedonians, the Messenians also participated, as I previously indicated in my account of Attica. They did not, however, join the Greeks in fighting the Gauls, since Cleonymus and the Spartans refused to conclude an alliance with them.