17.15 Yat, that; vakyam, speech; anudvegakaram, which causes no pain, which is not hurtful to creatures which is satyam, true; priya-hitam, agreeable and beneficial with regard to facts seen or unseen-.
'Speech' is alified by characteristics such as being not hurtful, etc. The ca (and) is used for grouping together the alifying characteristics. When a sentence is used in order to make another understand, if it happens to be avoid of one or two or three among the alities-truthfulness, agreeability, beneficialness, and non-hurtfulness-, then it is not austerity of speech.
As in the case of a truthful utterance there would occur a want of austerity of speech if it be lacking in one or two or three of the others, so also in the case of an agreeable utterance there would be no austerity of speech were it ot be without one or two or three of the others; and similarly, there would be no austerity of speech even in a beneficial utterance which is without one or two or three of the others.
What, again, is that austerity (of speech)? That utterance which is true as also not hurtful, and is agreeable and beneficial, is the highest austerity of speech: As for example, the utterance, 'Be calm, my boy. Practise study and yoga. Thery you will gain the highest.'
Svadhyaya-abhyasanam, the practice of the study of scriptures, as is enjoined; ca eva, as well; ucyate, in said to be; tapah, austerity; vanmayam, of speech.