Passage 2.26.3
Ἀσκληπιοῦ δὲ ἱερὰν μάλιστα εἶναι τὴν γῆν ἐπὶ λόγῳ συμβέβηκε τοιῷδε. Φλεγύαν Ἐπιδαύριοί φασιν ἐλθεῖν ἐς Πελοπόννησον πρόφασιν μὲν ἐπὶ θέᾳ τῆς χώρας, ἔργῳ δὲ κατάσκοπον πλήθους τῶν ἐνοικούντων καὶ εἰ τὸ πολὺ μάχιμον εἴη τῶν ἀνθρώπων· ἦν γὰρ δὴ Φλεγύας πολεμικώτατος τῶν τότε καὶ ἐπιὼν ἑκάστοτε ἐφʼ οὓς τύχοι τοὺς καρποὺς ἔφερε καὶ ἤλαυνε τὴν λείαν.
The reason why this land is especially sacred to Asclepius is said to be as follows. According to the Epidaurians, Phlegyas came to the Peloponnese ostensibly to view the region, but in reality as a spy, to observe the population and to determine whether most of its people were fit for war. For Phlegyas was indeed the most warlike man of that time, and he made attacks wherever chance led him, carrying off crops and driving away plunder.