Ṣaḍviṃśa Brāhmaṇa ("26th" book) 3.12

3.12

gāyatryām ṛci dve gāyatrasaṃhitākhye sāmanī kriyete | tasmāt puruṣaḥ prāṇena dvayaṃ prāṇanamapānanaṃ ca karoti | tasyaiva vivaraṇam | prāṇiti cāpāniti ceti | kakubuṣṇihau dve api ekameva chandaḥ | dvayorapi aṣṭāviṃśatyakṣarātmakatvāt | tatra kakubhi dvau prathamatṛtīyau pādāvaṣṭākṣarau madhyamaḥ pādo dvādaśākṣaraḥ | uṣṇihi tu prathamadvitīẏāvaṣṭākṣarau tṛtīyo dvādaśākṣara iti viśeṣaḥ | tatra dve saphapauṣkalākhye sāmanī kriyete | tasmāt pumān samānam aikye sat śrotram ekenaiva śrotrendriyeṇa dvedhaiva dvidhaiva purastāt paścācca śṛṇoti | anuṣṭubhi dve śyāvāśvāndhīgavanāmake sāmanī bhavataḥ | tasmāt puruṣo dvayaṃ satyamanṛtaṃ caikayā vācā karoti vadati |
tasyaiva vivaraṇam | satyaṃ cānṛtaṃ ca vadatīti | jagatyāṃ kāvākhyam ekaṃ sāma bhavati | tasmād adhiṣṭhānabhedād akṣiṇī dve satī samānam availakṣaṇyena purastādāyantaṃ padārthaṃ paśyataḥ | karaṇe kartṛtvopacāraḥ | na tu paścāt pṛṣṭhata āyantaṃ bhāvaṃ cakṣuṣā pumān paśyati | śrotreṇa yathā pṛṣṭhataḥ śabdaṃ śṛṇoti na tadvadityarthaḥ |
avaśiṣṭasya yajñāyajñīyasya mūrdhātmakatvaṃ darśayati—