Passage 4.27.11
Μεσσήνιοι δὲ ἐκτὸς Πελοποννήσου τριακόσια ἔτη μάλιστα ἠλῶντο, ἐν οἷς οὔτε ἐθῶν εἰσι δῆλοι παραλύσαντές τι τῶν οἴκοθεν οὔτε τὴν διάλεκτον τὴν Δωρίδα μετεδιδάχθησαν, ἀλλὰ καὶ ἐς ἡμᾶς ἔτι τὸ ἀκριβὲς αὐτῆς Πελοποννησίων μάλιστα ἐφύλασσον.
The Messenians were in exile from the Peloponnese for about three hundred years; during that time they neither abandoned their ancient customs in any visible respect nor altered their Doric dialect, but even to our own day they have preserved it in a purer form than all other Peloponnesians.