Kauṣītaki Upaniṣad 3.1.2

3.1.2

āyuruktaṃ yat sa prāṇa uktaḥ| nanu āyuṣaḥ prāṇatve'pi na prāṇasyāyuṣṭvaṃ yathā sāstrāyā gotve'pi na goḥ sāstrātvamityata āha, prāṇo vā āyuḥ prāṇa evāyuḥ na lakṣāṅgiguṇaguṇyādibhedaḥ | na cetadāyūṣa eva kintvamṛtatvasyāpītyāha prāṇa u vā amṛtaṃ amṛtamapi prāṇa eva| prāṇasyāyuṣṭumamṛtatvañcopapādayati, yāvat yāvantaṃ kālaṃ hi yasmāt asmin pratyakṣe śarīre śīrṇāvayave kalevare prāṇo vasati tāvadāyūḥ tāvantaṃ kālaṃ spaṣṭamanyat | idānīmamṛtatvamupapādayati, prāṇena hyeva yasmātprāṇenaiva na tu śarīreṇāpi amuṣmin parokṣe loke svargādau amṛtatvaṃ sukhaṃ prāpnoti spaṣṭaṃ | nanu prāṇasya kriyāśakterbhavataḥ kiṃ prajñayetyata āha, prajñayā jñānaśaktirūpeṇa satyaṃ satyavacanaṃ niṣprapañcaṃ brahma vā saṅkalpamidaṃ me syādityevaṃ rūpaṃ manasaḥ pracāramadhigacchatīti śeṣaḥ | evaṃ prajñādīnāmupayogamuktāyuṣṭāmṛtatvopāsanayoḥ phalamāha, sa prasiddha upāsako yaḥ yaḥ kaścinme mama indrasya prāṇātmano'pṛthagbhūtamāyuramṛtamiti vyākhyātaṃ upāste spaṣṭaṃ, ya upāste sa ityanvayaḥ, sarvamāyurasmin loka eti nikhilaṃ śatasaṃvatsaramāyurāpnoti | āyurupāsanasya