Maitrayaniya Upanishad 7.10.7

7.10.7

yā nāḍī hṛdayānnirgatā tāvadāyatau dīrghā yāvaccakṣurato'smiṃ ścakṣuṣi pratiṣṭhitā, sarato'syāmindrendrāṇyāviti vā sārayatyetāviti vā sāraṇī nāma nāḍī sañcaraṇamārgabhūtā ekāpi satī tayordvayoḥ savyadakṣiṇakṣi prāptyekatvāt dvidhocyate ityarthaḥ, ' athainayoreṣā sṛtiḥ sañcaraṇī yaiṣā hṛdayādūrddhā nāḍyuccarati ' (bṛhadā0) iti śrutyantaraṃ | evamanayorjāgratsvapnāvasthātmasañcaraṇamārgā uktāḥ | idānoṃ suptiprāptikrameṇāvasthātrayātītaṃ turīyaṃ padamekarasaṃ tattvamanayorvaktavyaṃ tadihārthārduktameveti siddhavatkṛtya prakṛtaṃ vedāvirbhāvaviṣayaṃ ślokajātamudāharati "manaḥ 0 evamāṅgaḥ" iti | udbuddhāryavāsanatayātmavivakṣānugṛhītayā buddhyā niyuktaṃ manaḥ kāyāgniṃ śarīrasthitasūkṣmarūpamagnimāhanti prabodhayati, sa kāyāgnirmārutaṃ vāyuṃ prāṇākhyaṃ prerayati vyāpārayati ghoṣavantamāpādayatītyarthaḥ | mārutastūrasi caran sañcaran mandraṃ svaraṃ ghoṣaṃ janayati, tataḥ khajāgniyogāt nirmanthanakāṣṭhaṃ khaja ityucyate, khajasthānīyenāgninā yogāddhṛdi uraḥpradeśe samprayuktaṃ samyagāloḍitaṃ tanmārutasvarūpaṃ manovṛttyuparaktaṃ prathamamaṇoḥ