Plutarch, On Preserving One's Health
7 = Moralia
125 D (tr. Frank Cole Babbitt):
Simonides used to say that he had never been sorry for having kept silent, but many a time for having spoken.
ὁ Σιμωνίδης ἔλεγε μηδέποτ᾿ αὐτῷ μεταμελῆσαι σιγήσαντι, φθεγξαμένῳ δὲ πολλάκις.
Plutarch, On Talkativeness
23 = Moralia
514 F (tr. W.C. Helmbold):
And over and above all else we must keep at hand and in our minds the saying of Simonides, that he had often repented of speaking, but never of holding his tongue.
ἐπὶ πᾶσι δὲ καὶ παρὰ ταῦτα πάντα δεῖ πρόχειρον ἔχειν καὶ μνημονεύειν τὸ Σιμωνίδειον ὅτι λαλήσας μὲν πολλάκις μετενόησε, σιωπήσας δ᾿ οὐδέποτε.
Cf. Plutarch, On the Education of Children
10 = Moralia
10 F (tr. Frank Cole Babbitt):
For, again, nobody was ever sorry because he kept silent, but hundreds because they talked.
καὶ γὰρ αὖ σιωπήσας μὲν οὐδεὶς μετενόησε, λαλήσαντες δὲ παμπληθεῖς.