Passage 10.32.14
ἐν δὲ τῇ Τιθορέων καὶ δὶς ἑκάστου τοῦ ἔτους τῇ Ἴσιδι πανήγυριν ἄγουσι, τὴν μὲν τῷ ἦρι, τὴν δὲ μετοπωρινήν· τρίτῃ δὲ ἡμέρᾳ πρότερον κατὰ ἑκατέραν τῶν πανηγύρεων, ὅσοις ἐστὶν ἐσελθεῖν ἄδεια, τὸ ἄδυτον ἐκκαθαίρουσι τρόπον τινὰ ἀπόρρητον, καὶ δὴ καὶ τῶν ἱερείων ἃ ἐπὶ τῆς προτέρας ἐνεβλήθη πανηγύρεως, τούτων ὁπόσα ἂν ὑπολειπόμενα εὕρωσι κομίζουσιν ἐς τὸ αὐτὸ ἀεὶ χωρίον καὶ κατορύσσουσιν ἐνταῦθα· δύο τε ἀπὸ τοῦ ἀδύτου στάδια ἐτεκμαιρόμεθα ἐς τοῦτο εἶναι τὸ χωρίον.
In Tithorea they hold a festival for Isis twice each year, one in the spring and the other in autumn. On the third day before each of these festivals, those who have permission to enter purify the sanctuary in a manner that must remain secret, and whatever remains they find of the sacrificial offerings presented at the previous festival, they carry to the same place every time and bury it there. I estimate this place to be about two stades distant from the sanctuary.