Maitrayaniya Upanishad 2.5.4

2.5.4

praveśaprakāramāha “sa vāyuḥ 0 prāviśat” iti | sa prajāpatirīśvaraḥ ātmānaṃ svarūpaṃ vāyuriva kṛtvā vāyuḥ prāṇaḥ prāṇavāyumupādhiṃ kurvaṃstadbhāvamāpanno vāyurivetyucyate ityamabhyantaraṃ prāviśadityarthaḥ | tathā ca śrutyantare ‘taṃ prapadābhyāṃ prāpadyata brahmemaṃ puruṣaṃ’ iti prāṇarūpaṃ brahmopakramyāmnāyate | evamapi bhastreva vāyunā pūrṇā na vyaceṣṭata, yadā śarīraṃ jātaṃ tadā kiṃ kṛtavānīśvarastadāha “sa ekaḥ 0 ucyate” iti | ekarūpaḥ san nāśakta, dehaṃ vicālayituṃ nāśaknot, sa punarātmānaṃ pañcadhā vibhajya kramākramābhyāṃ kriyābhedaṃ kurvan dehādikaṃ cālayannāste iti prāṇādiśabdaiḥ sa evocyata ityarthaḥ | ke te prāṇādayo vibhāgāḥ kiṃlakṣaṇāḥ kiṃkarmāṇaścetyapekṣāyāmāha “yaḥ prāṇaḥ 0 vyāna iti” iti | ityete pañca nirdiṣṭāḥ | athaiṣāṃ lakṣaṇaṃ kriyāñca darśayati “athāyaṃ 0 udānaḥ” | athaiṣāṃ madhye yo'yaṃ vāyurūrddhamutkrāmati nābherūrddhaṃ śiraḥparyantamuccaiḥ krāmati sañcarati mukhanāsikayorupalabhyamāna eṣa vāva saḥ eṣa eva prāṇaḥ prāṇasañjño vāyubheda