Passage 9.18.4
ἐν Μυσίᾳ τῇ ὑπὲρ Καΐκου πόλισμά ἐστι Πιονίαι, τὸν δὲ οἰκιστὴν οἱ ἐνταῦθα Πίονιν τῶν τινα ἀπογόνων τῶν Ἡρακλέους φασὶν εἶναι· μελλόντων δὲ ἐναγίζειν αὐτῷ καπνὸς αὐτόματος ἄνεισιν ἐκ τοῦ τάφου. ταῦτα μὲν οὖν συμβαίνοντα εἶδον, Θηβαῖοι δὲ καὶ Τειρεσίου μνῆμα ἀποφαίνουσι, πέντε μάλιστα καὶ δέκα ἀπωτέρω σταδίοις ἢ Οἰδίποδος τοῖς παισίν ἐστιν ὁ τάφος· ὁμολογοῦντες δὲ καὶ οὗτοι συμβῆναι Τειρεσίᾳ τὴν τελευτὴν ἐν τῇ Ἁλιαρτίᾳ, τὸ παρὰ σφίσιν ἐθέλουσιν εἶναι κενὸν μνῆμα.
In Mysia, above the Kaïkos, there is a small town called Pioniai. The inhabitants here say that their founder was Pionis, one of the descendants of Herakles. Whenever they intend to offer a sacrifice to him, smoke spontaneously ascends from his tomb. I myself have witnessed this occurring. The Thebans point out the tomb of Teiresias as well, situated approximately fifteen stadia farther away than that of the children of Oedipus. Yet, although even they admit that Teiresias died in the territory of Haliartos, they claim that the burial site in their land is an empty monument.