Passage 8.50.8
ἡμέραις δὲ ὕστερον τῆς ναυμαχίας οὐ πολλαῖς Φιλοποίμην καὶ ὁ σὺν αὐτῷ λόχος φυλάξαντες νύκτα ἀσέληνον τὸ στρατόπεδον τῶν Λακεδαιμονίων κατεμπιπρᾶσιν ἐν Γυθίῳ. ἐνταῦθα ἀπέλαβεν ἐν δυσχωρίαις Νάβις Φιλοποίμενά τε αὐτὸν καὶ ὅσοι περὶ αὐτὸν τῶν Ἀρκάδων ἦσαν· ἦσαν δὲ ἄλλως μὲν ἀγαθοὶ τὰ ἐς πόλεμον, ἀριθμὸν δὲ οὐ πολλοί.
Not many days after the naval battle, Philopoemen and the force accompanying him, taking advantage of a moonless night, attacked and set fire to the camp of the Lacedaemonians at Gythium. Here, Nabis caught Philopoemen himself and the Arcadians around him in difficult terrain. These Arcadians, though otherwise courageous soldiers, were few in number.