Passage 8.50.5
ἐν δὲ Λακεδαίμονι αὖθις ἐπανέστη τύραννος Νάβις, ὃς Πελοποννησίων πρώτοις ἐπέθετο Μεσσηνίοις· ἐπελθὼν δέ σφισιν ἐν νυκτὶ καὶ οὐδαμῶς τὴν ἔφοδον ἐλπίζουσιν εἷλε μὲν πλὴν τῆς ἀκροπόλεως τὸ ἄστυ, ἀφικομένου δὲ ἐς τὴν ὑστεραίαν στρατιᾷ Φιλοποίμενος ἐξέπεσεν ὑπόσπονδος ἐκ Μεσσήνης.
In Lacedaemon, however, Nabis again arose as a tyrant, who was the first among the Peloponnesians to attack the Messenians. He fell upon them by night, capturing their city—except the acropolis—while they were completely unprepared and unsuspecting of the assault. But on the following day, when Philopoemen arrived with an army, Nabis was forced by treaty to withdraw from Messene.