Passage 2.5.3
τὰ δὲ ἄλλα ἐς τὸν ποταμὸν Φλιάσιοι καὶ Σικυώνιοι λέγουσι, τὸ ὕδωρ ἔπηλυ καὶ οὐκ ἐγχώριον εἶναί οἱ· Μαίανδρον γὰρ κατιόντα ἐκ Κελαινῶν διὰ Φρυγίας καὶ Καρίας καὶ ἐκδιδόντα ἐς τὴν πρὸς Μιλήτῳ θάλασσαν ἐς Πελοπόννησον ἔρχεσθαι καὶ ποιεῖν τὸν Ἀσωπόν. οἶδα δὲ καὶ Δηλίων τοιοῦτο ἀκούσας ἕτερον, ὕδωρ ὃ καλοῦσιν Ἰνωπὸν εἶναί σφισιν ἐκ τοῦ Νείλου· καὶ δὴ καὶ αὐτὸν ἔχει τὸν Νεῖλον λόγος Εὐφράτην ὄντα ἐς ἕλος ἀφανίζεσθαι καὶ αὖθις ἀνιόντα ὑπὲρ Αἰθιοπίας Νεῖλον γίνεσθαι. Ἀσωποῦ μὲν πέρι τοιαῦτα ἤκουσα, ἐκ δὲ τοῦ Ἀκροκορίνθου
The Phliasians and the Sicyonians relate further traditions about this river, asserting that its water is foreign and not native to their land. They claim that the river Maeander, after flowing down from Celaenae through Phrygia and Caria and discharging its waters into the sea by Miletus, travels underground into the Peloponnese and forms the river Asopus. I have also heard a similar story told differently by the people of Delos, who say that the water of their river called the Inopus originates from the Nile. Indeed, there is even a story told about the Nile itself—that it is really the Euphrates, losing itself in a marsh, and then later emerging above Ethiopia, transforming into the Nile. Such, then, are the tales I have heard concerning the Asopus. But from Acrocorinth—