Passage 6.12.5
μετὰ δὲ τοῦ Ἱέρωνος τὰς εἰκόνας Ἀρεὺς ὁ Ἀκροτάτου Λακεδαιμονίων βασιλεὺς καὶ Ἄρατος ἕστηκεν ὁ Κλεινίου, καὶ αὖθις ἀναβεβηκώς ἐστιν Ἀρεὺς ἵππον. ἀνάθημα δὲ ὁ μὲν Κορινθίων ὁ Ἄρατος, Ἀρεὺς δὲ Ἠλείων ἐστί· καί μοι τοῦ λόγου τὰ πρότερα οὔτε τῶν ἐς Ἄρατον οὔτε τῶν ἐς Ἀρέα ἀμνημόνως ἔσχεν, Ἄρατος δὲ καὶ ἅρματι ἀνηγορεύθη νικῶν ἐν Ὀλυμπίᾳ.
After the images of Hiero stand Areus, son of Acrotatus, king of the Lacedaemonians, and Aratus, son of Cleinias; and nearby is Areus again, mounted on horseback. The dedication of Aratus is from the Corinthians, while that of Areus is from the Eleians. In my earlier account, I have not neglected what concerns either Aratus or Areus; moreover, Aratus was proclaimed victor at Olympia with a chariot.