Chandogya Upanishad 7.15

prāṇo vāva āśāyā bhūyān yathā vā arā nābhau samarpitā evam asmin prāṇe sarvaṃ samarpitam prāṇaḥ prāṇena yāti prāṇaḥ prāṇaṃ dadāti prāṇāya dadāti prāṇo ha pitā prāṇo mātā prāṇo bhrātā prāṇaḥ svasā prāṇa ācāryaḥ prāṇo brāhmaṇaḥ

'Spirit (prâna) is better than hope. As the spokes of a wheel hold to the nave, so does all this (beginning with names and ending in hope) hold to spirit. That spirit moves by the spirit, it gives spirit to the spirit. Father means spirit, mother is spirit, brother is spirit, sister is spirit, tutor is spirit, Brâhmana is spirit.

sa yadi pitaraṃ vā mātaraṃ vā bhrātaraṃ vā svasāraṃ vācāryaṃ vā brāhmaṇaṃ vā kiṃcid bhṛśam iva pratyāha dhik tvāstv ity evainam āhuḥ pitṛhā vai tvam asi mātṛhā vai tvam asi bhrātṛhā vai tvam asi svasṛhā vai tvam asy ācāryahā vai tvam asi brāhmaṇahā vai tvam asīti

'For if one says anything unbecoming to a father, mother, brother, sister, tutor or Brâhmana, then people say, Shame on thee! thou hast offended thy father, mother, brother, sister, tutor, or a Brâhmana.

atha yady apy enān utkrāntaprāṇāñchūlena samāsaṃ vyatisaṃdahet naivainaṃ brūyuḥ pitṛhāsīti na mātṛhāsīti na bhrātṛhāsīti na svasṛhāsīti nācāryahāsīti na brāhmaṇahāsīti

'But, if after the spirit has departed from them, one shoves them together with a poker, and burns them to pieces, no one would say, Thou offendest thy father, mother, brother, sister, tutor or a Brâhmana.

prāṇo hy evaitāni sarvāṇi bhavati sa vā eṣa evaṃ paśyann evaṃ manvāna evaṃ vijānann ativādī bhavati taṃ ced brūyur ativādy asīti ativādy asmīti brūyāt nāpahnuvīta

'Spirit then is all this. He who sees this, perceives this, and understands this, becomes an ativâdin. If people say to such a man, Thou art an ativâdin, he may say, I am an ativâdin; he need not deny it.'