Passage 9.22.7
εἶναι δὲ αὐτὸν ἁλιέα, καὶ ἐπεὶ τῆς πόας ἔφαγε, δαίμονα ἐν θαλάσσῃ γενέσθαι καὶ ἀνθρώποις τὰ ἐσόμενα ἐς τόδε προλέγειν οἵ τε ἄλλοι πιστὰ ἥγηνται καὶ οἱ τὴν θάλασσαν πλέοντες πλεῖστα ἀνθρώπων ἐς τὴν Γλαύκου μαντικὴν κατὰ ἔτος ἕκαστον λέγουσι. Πινδάρῳ δὲ καὶ Αἰσχύλῳ πυνθανομένοις παρὰ Ἀνθηδονίων, τῷ μὲν οὐκ ἐπὶ πολὺ ἐπῆλθεν ᾆσαι τὰ ἐς Γλαῦκον, Αἰσχύλῳ δὲ καὶ ἐς ποίησιν δράματος ἐξήρκεσε.
They say that he was a fisherman who, after eating a certain herb, became a divine being dwelling in the sea, and thenceforth foretold future events to men. Both others consider these prophecies trustworthy, and sailors especially relate numerous stories each year about Glaucus' oracle. When Pindar and Aeschylus inquired about him from the people of Anthedon, the former was moved only briefly to sing about matters regarding Glaucus, whereas Aeschylus found in this material sufficient inspiration to compose a dramatic work.