Chandogya Upanishad 6.8.6

6.8.6

tasya kva mūlaṃ syād anyatrādbhyaḥ \
adbhiḥ somya śuṅgena tejo mūlam anviccha \
tejasā somya śuṅgena sanmūlam anviccha \
sanmūlāḥ somyemāḥ sarvāḥ prajāḥ sad āyatanāḥ satpratiṣṭhāḥ \
yathā nu khalu somyemās tisro devatāḥ puruṣaṃ prāpya trivṛt trivṛd ekaikā bhavati tad uktaṃ purastād eva bhavati \
asya somya puruṣasya prayato vāṅ manasi saṃpadyate manaḥ prāṇe prāṇas tejasi tejaḥ parasyāṃ devatāyām \\608.6\

‘Where could its root be, apart from water? Dear boy, with water as the shoot, look for fire as the root; with fire as the shoot, look for Being as the root. All these creatures, dear boy, have Being as their root, have Being as their abode, and have Being as their support. How, dear boy, each of these three deities, on reaching man, becomes threefold has been explained to you earlier. When this man is about to depart, dear boy, his speech merges in the mind, mind in Prāṇa, Prāṇa in fire, and fire in the supreme deity.footnote{Now, by the description of a man’s death, the doctrine of Being is further taught. At the time of death speech ceases to function first, but the mind continues to function; for it is said that what}