anudvegakaraṃ vākyaṃ satyaṃ priyahitaṃ ca yat |svādhyāyābhyasanaṃ caiva vāṅmayaṃ tapa ucyate ||
Speech that causes no distress, that is truthful, pleasing and beneficial, together with the regular practice of scriptural study and recitation — this is called the austerity of speech.
Explanation
Krishna is describing three kinds of austerity (tapas) according to the three qualities of nature (guṇa). After the austerity of the body, he turns to speech: words should be non-agitating, true, kind and useful, joined with regular study and recitation of sacred texts (svādhyāya). The verse sets these qualities side by side, so speech must meet all of them, not only truth.