Manava Dharmashastra 6.70

6.70

brāhmaṇaśabdena jātidharmatāmāha | na parivrājakasyaiva vidhirayam | trayo'pi | tribhya ūrdhvaṃ phalādhikyam, trayastvavaśyaṃ kartavyāḥ | vyāhṛtayaḥ "oṃkārapūrvikā" ityatra yā uktāḥ | praṇava oṃkāraḥ | tairyuktāḥ | prāṇāyāmakāla etadbhāvatavyam | ete trividhāḥ kumbhakarecakapūrakākhyāḥ | tatra ca mukhyasya nāsikyasya ca vāyorbahirniṣkramaṇanirodhena kumbhakapūrakākhyāḥ anucchvasato bahirnerantaryeṇa vāyorutsargeṇa recako bhavati | avadhirrdvitīyādhyāye nidarśitaḥ | yadi vā tapasā punaryāvatā kālena na pīḍopajāyate |

Even three ‘breath-suspensions,’ accompanied by the three ‘vyāhṛti’-syllables and the syllable ‘om’, when duly performed, should be regarded as the highest austerity for the Brāhmaṇa.—(70)

Medhātithi’s commentary (manubhāṣya):
By using the term ‘brāhmaṇa’ the text implies that what is mentioned constitutes the duty of the whole caste, and is not restricted to the Renunciate only.

‘Even three’—more than three lead to more excellent results; three are absolutely necessary.

‘Vyāhṛti syllables’— those mentioned under 2.81.

‘Praṇava’—the syllable ‘om’.

The breath-suspensions are to be ‘accompanied by these’.—This indicates the duration of the breath-suspension.

These breath-suspensions are of three kinds, named ‘Kumbhaka’ (total suspension), ‘Pūraka’ (inhaling) and ‘Recaka’ (exhaling). The total suppression of air passing out of the mouth and the nostrils constitutes the (inhalation and suspension); and when the man does not inhale breath but continuously keeps on exhaling, it is called ‘Recaka exhalation.’ The exact duration of each of these has been described under Discourse II. Or, in view of its being spoken of as ‘austerity,’ it may be continued till it becomes actually painful.—(70)

Cf. 2.74.

This verse is quoted in Madanapārijāta (p. 68).

Comparative notes by various authors
Vaśiṣṭha (10.5).—‘The one syllable om is the best Veda; the suppression of breath is the highest austerity; living on alms is better than fasting; compassion is preferable to liberality.’