Speech causing no agitation, true (satya), pleasant, and beneficial, And the practice of the study of the scriptures (svādhyāya); this is called the austerity (tapas) of speech.
Speaking truth without offense, giving comfort, and reciting sacred lore is called verbal penance.
(15) Words that do not cause disquiet, [words] truthful, kind, and pleasing, the constant practice too of sacred recitation,—[this] is the penance of the tongue.
17.15 That speech which causes no pain, which is true, agreeable and beneficial; as well as the practice of study of the scriptures,-is said to be austerity of speech.
17.15 Speech that causes no shock (hurt and fear etc.) and which is true, pleasant and beneficial, and also the practice of recitation of the scriptures are called the austerity of speech.
17.15 Speech which causes no excitement, truthful, pleasant and beneficial, the practice of the study of the Vedas, are called austerity of speech.