Passage 1.28.5
καθὸ καὶ ὁ Ἄρειος πάγος. ἔστι δὲ Ἄρειος πάγος καλούμενος, ὅτι πρῶτος Ἄρης ἐνταῦθα ἐκρίθη, καί μοι καὶ ταῦτα δεδήλωκεν ὁ λόγος ὡς Ἁλιρρόθιον ἀνέλοι καὶ ἐφʼ ὅτῳ κτείνειε. κριθῆναι δὲ καὶ ὕστερον Ὀρέστην λέγουσιν ἐπὶ τῷ φόνῳ τῆς μητρός· καὶ βωμός ἐστιν Ἀθηνᾶς Ἀρείας, ὃν ἀνέθηκεν ἀποφυγὼν τὴν δίκην. τοὺς δὲ ἀργοὺς λίθους, ἐφʼ ὧν ἑστᾶσιν ὅσοι δίκας ὑπέχουσι καὶ οἱ διώκοντες, τὸν μὲν Ὕβρεως τὸν δὲ Ἀναιδείας αὐτῶν ὀνομάζουσι.
Hence also the Areopagus. It is called the "Hill of Ares" because Ares was the first to be tried there; the story has also informed me of these matters, that he killed Halirrhothius and why he slew him. They say that afterwards Orestes too was tried here for the murder of his mother. There is an altar dedicated to Athena Areia, which Orestes set up after being acquitted. As for the rough stones upon which defendants and their accusers stand during their trial, these they have named Respectively the Stone of Insolence (Hybris) and the Stone of Shamelessness (Anaideia).