Taittirīyopaniṣat 03.08

annaṃ na nindyāt। tad vratam। prāṇo vā annam। śarīram annādam। prāṇe śarīraṃ pratiṣṭhitam। śarīre prāṇaḥ pratiṣṭhitaḥ। tad etad annam anne pratiṣṭhitam। sa ya etad annam anne pratiṣṭhitaṃ veda pratitiṣṭhati। annavān annādo bhavati। mahān bhavati prajayā paśubhir brahmavarcasena। mahān kīrtyā ॥8॥

One should not revile food; that is the vow. The vital breath is indeed food; the body is the eater of food. In the vital breath, the body is established; in the body, the vital breath is established. Thus, this food is established in food. He who knows that this food is established in food becomes established. He becomes possessed of food and an eater of food. He becomes great by progeny, by cattle, by spiritual lustre, and great by fame.

Taittirīya Bhāshya 03.08

Testimonial elaborates, reiterating how sage Brugu recognized the Lord's presence in sequence, as one of many forms, from food all the way to bliss. It is the all-pervading Lord Viṣṇu who perceives all the time. Austerity (tapa) arises from the very nature of knowledge, while discernment is from discrimination. Through the ascetic practice of seeking knowledge, one attains the Lord Janardana.

"cakṣuḥ sa caṣṭe yad viṣṇuḥ śrotraṃ śrotṛtvato vibhuḥ। vāk ca vaktṛtvato nityaṃ mano mantr̥tvatastathā॥

"He, the all-pervading Lord Viṣṇu perceives all the time - seeing through the eye as observer, hears through the ear as the hearer, speech (is his) as the speaker, and mind (is his) as the thinker, thus.

tapo jñānasvarūpatvād vijñānaṃ tu vivecanāt। jñānānusandhānarūpatapasā taṃ janārdanam॥

Austerity (tapa) arises from the very nature of knowledge, while discernment is from discrimination. Through the ascetic practice of seeking knowledge, one attains the Lord Janardana.

kramād bhṛgur vyajānāt tam annādi-bahurūpiṇam। evaṃ vijānaṃs taṃ viṣṇuṃ tasmiṃs tu pratitiṣṭhati॥

Sage Bhṛgu, in sequence, recognized him as one of many forms, beginning with food. Thus, knowing him as the Lord Viṣṇu, one remains established in him.

mukto bhūtvā'nnavāṁś ca syād annādaś ca sadaiva tu। annanāmā tu bhagavān vidvān tam upajīvati॥ tadvāṁś ca tena guptatvād ... ॥

Having attained liberation, one may possess and consume food always; but the wise Lord, called by the name of food, subsists on him, taking his share from him, protected, ...