Passage 5.11.9
μέτρα δὲ τοῦ ἐν Ὀλυμπίᾳ Διὸς ἐς ὕψος τε καὶ εὖρος ἐπιστάμενος γεγραμμένα οὐκ ἐν ἐπαίνῳ θήσομαι τοὺς μετρήσαντας, ἐπεὶ καὶ τὰ εἰρημένα αὐτοῖς μέτρα πολύ τι ἀποδέοντά ἐστιν ἢ τοῖς ἰδοῦσι παρέστηκεν ἐς τὸ ἄγαλμα δόξα, ὅπου γε καὶ αὐτὸν τὸν θεὸν μάρτυρα ἐς τοῦ Φειδίου τὴν τέχνην γενέσθαι λέγουσιν. ὡς γὰρ δὴ ἐκτετελεσμένον ἤδη τὸ ἄγαλμα ἦν, ηὔξατο ὁ Φειδίας ἐπισημῆναι τὸν θεὸν εἰ τὸ ἔργον ἐστὶν αὐτῷ κατὰ γνώμην· αὐτίκα δʼ ἐς τοῦτο τοῦ ἐδάφους κατασκῆψαι κεραυνόν φασιν, ἔνθα ὑδρία καὶ ἐς ἐμὲ ἐπίθημα ἦν ἡ χαλκῆ.
Although I am familiar with the recorded measurements of Zeus at Olympia, both in height and breadth, I will not include praise of those who measured it; for even the dimensions they state fall greatly short of the impression conveyed to those who behold the statue. Indeed, it is said that the god himself provided testimony to the art of Pheidias. For after the statue had already been completed, Pheidias prayed that the god might reveal a sign whether his work was pleasing to him; at once, they say, a thunderbolt descended onto that spot of the floor, where even in my time stood a bronze hydria covering the place.