Meditations 1.12.1
Marcus Aurelius, recalling Alexander the Platonist
Παρὰ Ἀλεξάνδρου τοῦ Πλατωνικοῦ τὸ μὴ πολλάκις μηδὲ χωρὶς ἀνάγκης λέγειν πρός τινα ἢ ἐν ἐπιστολῇ γράφειν ὅτι ἄσχολός εἰμι, μηδὲ διὰ τούτου τοῦ τρόπου συνεχῶς παραιτεῖσθαι τὰ κατὰ τὰς πρὸς τοὺς συμβιοῦντας σχέσεις καθήκοντα, προβαλλόμενον τὰ περιεστῶτα πράγματα.
From Alexander the Platonist: not often telling someone, or writing in a letter, ‘I have no time,’ and never without necessity; nor using this device to evade continually the duties arising from my relations with those I live among, by putting forward the business pressing upon me.