Passage 1.37.3
πρὶν δὲ ἢ διαβῆναι τὸν Κηφισὸν Θεοδώρου μνῆμά ἐστι τραγῳδίαν ὑποκριναμένου τῶν καθʼ αὑτὸν ἄριστα . ἀγάλματα δὲ ἐπὶ τῷ ποταμῷ Μνησιμάχης, τὸ δὲ ἕτερον ἀνάθημα κειρομένου οἱ τὴν κόμην τοῦ παιδός ἐστι τῷ Κηφισῷ· καθεστάναι δὲ ἐκ παλαιοῦ καὶ τοῖς πᾶσι τοῦτο Ἕλλησι τῇ Ὁμήρου τις ἂν τεκμαίροιτο ποιήσει, ὃς τὸν Πηλέα εὔξασθαί φησι τῷ Σπερχειῷ κερεῖν ἀνασωθέντος ἐκ Τροίας Ἀχιλλέως τὴν κόμην.
Before crossing the Cephisus is the tomb of Theodorus, who excelled beyond all others of his time in the performing of tragedy. By the river stand statues: one of Mnesimache, and another, dedicated as an offering, depicting a boy having his hair cut in honor of the Cephisus. That this custom of haircutting was established from ancient times among all the Greeks may be inferred from the poetry of Homer, who relates how Peleus vowed to cut Achilles’ hair for the river Spercheius, should his son return safely from Troy.