Taittirīyopaniṣat 03.02
स तपोऽतप्यत। स तपस्तप्त्वा। अन्नं ब्रह्मेति व्यजानात्। अन्नाद्ध्येव खल्विमानि भूतानि जायन्ते। अन्नेन जातानि जीवन्ति। अन्नं प्रयन्त्यभिसंविशन्तीति। तद्विज्ञाय। पुनरेव वरुणं पितरमुपससार। अधीहि भगवो ब्रह्मेति। तगं होवाच। तपसा ब्रह्म विजिज्ञासस्व। तपो ब्रह्मेति ॥२॥
sa tapo'tapyata। sa tapastaptvā। annaṃ brahmeti vyajānāt। annāddhyeva khalvimāni bhūtāni jāyante। annena jātāni jīvanti। annaṃ prayantyabhisaṃviśantīti। tadvijñāya। punareva varuṇaṃ pitaramupasasāra। adhīhi bhagavo brahmeti। taṃ hovāca। tapasā brahma vijijñāsasva। tapo brahmeti ॥2॥
[स (sa) - he; तपः (tapaḥ) - austerity; अतप्यत (atapyata) - practiced; स (sa) - he; तपः (tapaḥ) - austerity; तप्त्वा (taptvā) - having performed; अन्नम् (annam) - food; ब्रह्म (brahma) - Brahman; इति (iti) - thus; व्यजानात् (vyajānāt) - he understood; अन्नात् (annāt) - from food; हि (hi) - indeed; एव (eva) - only; खलु (khalu) - indeed; इमानि (imāni) - these; भूतानि (bhūtāni) - beings; जायन्ते (jāyante) - are born; अन्नेन (annena) - by food; जातानि (jātāni) - born; जीवन्ति (jīvanti) - live; अन्नम् (annam) - food; प्रयन्ति (prayanti) - depart; अभिसंविशन्ति (abhisaṃviśanti) - enter into; इति (iti) - thus; तत् (tat) - that; विज्ञाय (vijñāya) - having known; पुनः (punaḥ) - again; एव (eva) - only; वरुणम् (varuṇam) - Varuṇa; पितरम् (pitaram) - father; उपससार (upasasāra) - approached; अधीहि (adhīhi) - teach; भगवः (bhagavaḥ) - O venerable one; ब्रह्म (brahma) - Brahman; इति (iti) - thus; तं (taṃ) - him; होवाच (hovāca) - he said; तपसा (tapasā) - by austerity; ब्रह्म (brahma) - Brahman; विजिज्ञासस्व (vijijñāsasva) - seek to know; तपः (tapaḥ) - austerity; ब्रह्म (brahma) - Brahman; इति (iti) - thus;]
He practiced austerity. After performing austerity, he realized, "Food is Brahman." Indeed, it is from food that all these beings are born; by food, they live; and into food, they finally merge. Understanding this, he again approached his father Varuṇa and said, "O revered one, teach me about Brahman." Varuṇa replied, "Seek to know Brahman through austerity; austerity itself is Brahman."
