Passage 8.41.8
ναῶν δὲ ὅσοι Πελοποννησίοις εἰσί, μετά γε τὸν ἐν Τεγέᾳ προτιμῷτο οὗτος ἂν τοῦ λίθου τε ἐς κάλλος καὶ τῆς ἁρμονίας ἕνεκα. τὸ δὲ ὄνομα ἐγένετο τῷ Ἀπόλλωνι ἐπικουρήσαντι ἐπὶ νόσῳ λοιμώδει, καθότι καὶ παρὰ Ἀθηναίοις ἐπωνυμίαν ἔλαβεν Ἀλεξίκακος ἀποτρέψας καὶ τούτοις τὴν νόσον.
Among all the temples in the Peloponnese, next to the one at Tegea, this temple would be most esteemed both for the beauty of its stone and for the harmony of its construction. It acquired its name because Apollo gave assistance against a plague epidemic, just as among the Athenians he took the surname Alexikakos ("Averter of Evil") for having turned away disease from them also.