Passage 1.42.2
τῆς δὲ ἑστίας ἐγγὺς ταύτης ἐστὶ λίθος, ἐφʼ οὗ καταθεῖναι λέγουσιν Ἀπόλλωνα τὴν κιθάραν Ἀλκάθῳ τὸ τεῖχος συνεργαζόμενον. δηλοῖ τέ μοι καὶ τόδε ὡς συνετέλουν ἐς Ἀθηναίους Μεγαρεῖς· φαίνεται γὰρ τὴν θυγατέρα Ἀλκάθους Περίβοιαν ἅμα Θησεῖ πέμψαι κατὰ τὸν δασμὸν ἐς Κρήτην. τότε δὲ αὐτῷ τειχίζοντι, ὥς φασιν οἱ Μεγαρεῖς, συνεργάζεταί τε Ἀπόλλων καὶ τὴν κιθάραν κατέθηκεν ἐπὶ τὸν λίθον· ἢν δὲ τύχῃ βαλών τις ψηφῖδι, κατὰ ταὐτὰ οὗτός τε ἤχησε καὶ κιθάρα κρουσθεῖσα.
Near this hearth there lies a stone, on which, they say, Apollo laid down his lyre while assisting Alcathous in building the wall. The following also demonstrates to me that the Megarians cooperated with the Athenians: for it appears that Alcathous' daughter Periboea along with Theseus was sent as part of the tribute to Crete. When Alcathous was building the wall, according to the Megarians, Apollo aided him in the task and set his lyre upon the stone. If anyone should strike this stone with a pebble, it emits a ringing sound identical to that of a lyre struck.