अनुद्वेगकरं वाक्यं सत्यं प्रियहितं च यत्।स्वाध्यायाभ्यसनं चैव वाङ्मयं तप उच्यते।।17.15।।
That speech which causes no pain, which is true, agreeable, and beneficial; as well as the practice of studying the scriptures—is said to be the austerity of speech.
Osho’s Commentary
Then, the austerity of speech. Your words should be such that they do not create agitation in others. They should be truthful. But not just truthful; they should also be pleasant and beneficial. To speak a harsh truth can be a form of violence. The art is to speak the truth with love, with skill, in a way that helps, not hurts. And also, the regular study of the scriptures. To be in communion with the words of the awakened ones is a great purification of speech and mind.