“Speech that is factual, true, beneficial, and endearing to others is spoken at the proper time. Even if speech is true, if it is harmful and unbeneficial, the Tathagata does not utter it.”
Canonical Pali Original: Yaṃ vācaṃ jānāti bhūtaṃ tacchaṃ atthasañhitaṃ piyā manāpā paresaṃ, tatra kālaññū hoti tassā vācāya veyyākaraṇāya.
— Gautam Buddha
The Awakened One, Founder of Dhamma
Delivered to Prince Abhaya at Rajagaha, defining the criteria for ethical, compassionate, and constructive speech (Samma Vaca).