Bhagavad Gita Chapter 17, Verse 15

अनुवेदकं च वाक्यं सत्यं प्रियहितं च यत् | स्वाध्यायाभ्यसनं चैव वाङ्मयं तप उच्यते ||

anuvedakaṁ ca vākyaṁ satyaṁ priyahitaṁ ca yat svādhyāyābhyasanaṁ caiva vāṅmayaṁ tapa ucyate

Speech that is not causing pain, truthful, pleasant, and beneficial, and the study of scriptures—this is called speech austerity.

Krishna describes speech austerity—austerity of speech. 'Anuvedakaṁ ca vākyaṁ satyaṁ priyahitaṁ ca yat'—speech (vākyam) that is not causing pain (anuvedakam), truthful (satyam), pleasant (priya), and beneficial (hitam). 'Svādhyāyābhyasanaṁ caiva'—and the study (svādhyāya) and practice (abhyasanam) of scriptures. 'Vāṅmayaṁ tapa ucyate'—this is called (ucyate) speech austerity (vāṅmayam tapas). Speech austerity involves speaking truthfully, pleasantly, and beneficially, without causing pain, and studying sacred texts. This is discipline of speech—using words for truth and benefit rather than harm. Understanding this helps you recognize and practice speech austerity.