Enchiridion · §36

ὥσπερ τὸ "ἡμέρα ἐστί" καὶ "νύξ ἐστιν" πρὸς μὲν τὴν κοινωνίαν κρεάτων πολλοῦ ἄξια, πρὸς δὲ τὸ τῆς κοινωνίας πνεῦμα ἀνάξια· οὕτω τὸ τὰ σιτία ἐκλέγεσθαι τὰ χρησιμώτατα πρὸς τὸ σῶμα πρὸς μὲν τὴν σωτηρίαν τοῦ σώματος ἄξιον, πρὸς δὲ τὸ κοινωνικὸν τῆς ἑστιάσεως ἀνάξιον. ὅταν οὖν μετά τινος δειπνῇς, μέμνησο μὴ μόνον τὴν πρὸς τὸ σῶμα ἀξίαν τῶν παρατεθέντων σκοπεῖν, ἀλλὰ καὶ τὴν πρὸς τὸν ἑστιῶντα αἰδῶ τηρεῖν.

hōsper to 'hēmera esti' kai 'nux estin' pros men tēn koinōnian kreatōn pollou axia, pros de to tēs koinōnias pneuma anaxia; houtō to ta sitia eklegesthai ta chrēsimōtata pros to sōma pros men tēn sōtērian tou sōmatos axion, pros de to koinōnikon tēs hestiaseōs anaxion.

Saying 'it is day' or 'it is night' is highly useful for the purpose of dividing day from night, but it is worthless for the purpose of genuine social connection. In the same way, choosing the most nourishing food at a dinner may be appropriate for the body's sake, but doing so in a way that snubs your host is socially worthless. When you dine with another person, remember to honor not only the physical value of what is served but also the respect owed to the one who is hosting you.

— Enchiridion 36

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