Passage 2.22.5
προελθόντι δὲ οὐ πολὺ τάφος ἐστὶν Ἄργου Διὸς εἶναι δοκοῦντος καὶ τῆς Φορωνέως Νιόβης· μετὰ δὲ ταῦτα Διοσκούρων ναός. ἀγάλματα δὲ αὐτοί τε καὶ οἱ παῖδές εἰσιν Ἄναξις καὶ Μνασίνους, σὺν δέ σφισιν αἱ μητέρες Ἱλάειρα καὶ Φοίβη, τέχνη μὲν Διποίνου καὶ Σκύλλιδος , ξύλου δὲ ἐβένου· τοῖς δʼ ἵπποις τὰ μὲν πολλὰ ἐβένου καὶ τούτοις, ὀλίγα δὲ καὶ ἐλέφαντος πεποίηται.
Proceeding a short distance further, there is a tomb said to belong to Argos, reputedly the son of Zeus, and also to Niobe, daughter of Phoroneus; beyond this lies a temple of the Dioscuri. The statues in it represent themselves and their sons, Anaxis and Mnasinous, along with their mothers, Hilaeira and Phoebe. These statues, carved from ebony, are the work of Dipoenus and Scyllis. The horses also are mostly made of ebony, but with certain parts having been fashioned from ivory.