Enchiridion · §39

μέτρον κτήσεως σώματός ἐστιν ἑκάστῳ ὅσον χρεία· οὕτω δὴ καὶ ἐν τῷ περὶ τὸ σῶμα ἐπὶ τοῦ χρείου ἵστα, ἵνα μὴ ὡς εἰς κατωφερὲς φέρῃ σε ἡ ὑπεροχή.

metron ktēseōs sōmatos estin hekastō hoson chreia; houtō dē kai en tō peri to sōma epi tou chreiou hista, hina mē hōs eis katōpheres pherē se hē huperochē.

The measure of possessions for each person's body is whatever nature requires; stop there when it comes to the body, so that its excess does not carry you downhill.

— Enchiridion 39

Source: Greek (Schenkl/Oldfather critical edition tradition) + Long 1877 English translation