Passage 3.25.7
ἀναθήματα δὲ ἄλλα τέ ἐστιν ἐπὶ Ταινάρῳ καὶ Ἀρίων ὁ κιθαρῳδὸς χαλκοῦς ἐπὶ δελφῖνος. τὰ μὲν οὖν ἐς αὐτὸν Ἀρίονα καὶ τὰ ἐπὶ τῷ δελφῖνι Ἡρόδοτος εἶπεν ἀκοὴν ἐν τῇ Λυδίᾳ συγγραφῇ· τὸν δὲ ἐν Ποροσελήνῃ δελφῖνα τῷ παιδὶ σῶστρα ἀποδιδόντα, ὅτι συγκοπέντα ὑπὸ ἁλιέων αὐτὸν ἰάσατο, τοῦτον τὸν δελφῖνα εἶδον καὶ καλοῦντι τῷ παιδὶ ὑπακούοντα καὶ φέροντα, ὁπότε ἐποχεῖσθαί οἱ βούλοιτο.
At Taenarum there are various dedications, including a bronze statue of Arion the citharode riding upon a dolphin. Herodotus has recounted the story concerning Arion himself and the matter of the dolphin, based on hearsay, in his work about Lydia. As for the dolphin at Poroselene, which rendered thanks to the boy because the boy had healed it after fishermen wounded it, I myself saw this dolphin; it obeyed when the boy called it and carried him whenever he wished to ride.