Passage 10.19.5
Γαλατῶν δὲ τῆς ἐς τὴν Ἑλλάδα ἐπιστρατείας ἔχει μέν τινα μνήμην καὶ ἡ ἐς τὸ βουλευτήριον ἡμῖν τὸ Ἀττικὸν συγγραφή· προάγειν δὲ ἐς τὸ σαφέστερον τὰ ἐς αὐτοὺς ἠθέλησα ἐν τῷ λόγῳ τῷ ἐς Δελφούς, ὅτι ἔργων τῶν ἐπὶ τοὺς βαρβάρους τὰ μέγιστα Ἕλλησιν ἐνταῦθα ἦν. ὑπερόριον μὲν οἱ Κελτοὶ στρατείαν πρώτην ὑπὸ ἡγεμόνι ἐποιήσαντο Καμβαύλῃ· προελθόντες δὲ ἄχρι τῆς Θρᾴκης τὸ πρόσω τῆς πορείας οὐκ ἀπεθάρσησαν, καταγνόντες αὑτῶν ὅτι ὀλίγοι τε ἦσαν καὶ οὐκ ἀξιόμαχοι κατʼ ἀριθμὸν Ἕλλησιν.
Regarding the expedition of the Gauls against Greece, there is some mention even in the Attic record which is kept in our Council-house at Athens, but I have chosen to explain their history more clearly in my narrative concerning Delphi, because at that place occurred the greatest of the deeds done by the Greeks against these barbarians. The Celts undertook their first foreign campaign under the leader named Kambaules; however, after advancing as far as Thrace, they did not dare to proceed further, realizing they were few in number and insufficient as a force capable of matching the Greeks.