Passage 1.35.8
ἐπεὶ δέ σφισιν ἐναντιούμενος ἀπέφαινον ἐν Γαδείροις εἶναι Γηρυόνην, οὗ μνῆμα μὲν οὔ, δένδρον δὲ παρεχόμενον διαφόρους μορφάς, ἐνταῦθα οἱ τῶν Λυδῶν ἐξηγηταὶ τὸν ὄντα ἐδείκνυον λόγον, ὡς εἴη μὲν ὁ νεκρὸς Ὕλλου, παῖς δὲ Ὕλλος εἴη Γῆς, ἀπὸ τούτου δὲ ὁ ποταμὸς ὠνομάσθη· Ἡρακλέα δὲ διὰ τὴν παρʼ Ὀμφάλῃ ποτὲ ἔφασαν δίαιταν Ὕλλον ἀπὸ τοῦ ποταμοῦ καλέσαι τὸν παῖδα.
When, however, objecting to them, I pointed out that Geryon was in Gadeira, where no tomb existed, but only a tree taking various forms, the Lydian interpreters related here the real tradition: that the corpse belonged rather to Hyllus, and that Hyllus was a son of Earth, and from him the river was named. They further claimed that, because of his former stay with Omphale, Heracles later named his own son Hyllus after this river.