CHAPTER 15 VERSE 15
अनुद्वेगकरं वाक्यं सत्यं प्रियहितं च यत् ।
स्वाध्यायाभ्यसनं चैव वाङ्मयं तप उच्यते ॥१५॥
satyaṁ priya-hitaṁ ca yat
vāṅ-mayaṁ tapa ucyate
anudvega—not agitating; karam—producing; vākyam—words; satyam—truthful; priya—dear; hitam—beneficial; ca—also; yat—which; svādhyāya—Vedic study; abhyasanam—practice; ca—also; eva—certainly; vāṅmayaṁ—of the voice; tapaḥ—austerity; ucyate—is said to be.
Austerity of speech consists in speaking truthfully and beneficially and in avoiding speech that offends. One should also recite the Vedas regularly.