Passage 9.25.6
τοσοῦτο δὲ δηλῶσαί με καὶ ἐς ἅπαντας ἐκώλυσεν οὐδέν, ἥντινα λέγουσιν ἀρχὴν οἱ Θηβαῖοι γενέσθαι τοῖς δρωμένοις. πόλιν γάρ ποτε ἐν τούτῳ φασὶν εἶναι τῷ χωρίῳ καὶ ἄνδρας ὀνομαζομένους Καβείρους, Προμηθεῖ δὲ ἑνὶ τῶν Καβείρων καὶ Αἰτναίῳ τῷ Προμηθέως ἀφικομένην Δήμητρα ἐς γνῶσιν παρακαταθέσθαι σφίσιν· ἥτις μὲν δὴ ἦν ἡ παρακαταθήκη καὶ τὰ ἐς αὐτὴν γινόμενα, οὐκ ἐφαίνετο ὅσιόν μοι γράφειν, Δήμητρος δʼ οὖν Καβειραίοις δῶρόν ἐστιν ἡ τελετή.
But nothing at all prevented me from making known at least this much to all people, namely, the origin which the Thebans claim for these rites. For they say that once there was a city in this place, and in it men called Cabeiri; Demeter, arriving at Prometheus—one of the Cabeiri—and Aetnaeus, the son of Prometheus, entrusted something sacred to them. Concerning the nature of this trust and the rites performed in connection with it, I did not consider it lawful for me to write. Nevertheless, the initiation (telete) is Demeter’s gift to the Cabeiri.