Taittirīyopaniṣat 03.08

अन्नं न निन्द्यात्। तद् व्रतम्। प्राणो वा अन्नम्। शरीरमन्नादम्। प्राणे शरीरं प्रतिष्ठितम्। शरीरे प्राणः प्रतिष्ठितः। तदेतदन्नमन्ने प्रतिष्ठितम्। स य एतदन्नमन्ने प्रतिष्ठितं वेद प्रतितिष्ठति। अन्नवानन्नादो भवति। महान् भवति प्रजया पशुभिर्ब्रह्मवर्चसेन। महान् कीर्त्या ॥८॥

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.

"चक्षुः स चष्टे यद् विष्णुः श्रोत्रं श्रोतृत्वतो विभुः। वाक् च वक्तृत्वतो नित्यं मनो मन्तृत्वतस्तथा॥

"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.

तपो ज्ञानस्वरूपत्वाद् विज्ञानं तु विवेचनात्। ज्ञानानुसन्धानरूपतपसा तं जनार्दनम्॥

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.

क्रमाद् भृगुर्व्यजानात् तमन्नादिबहुरूपिणम्। एवं विजानंस्तं विष्णुं तस्मिंस्तु प्रतितिष्ठति॥

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.

मुक्तो भूत्वाऽन्नवांश्च स्यादन्नादश्च सदैव तु। अन्ननामा तु भगवान् विद्वान् तमुपजीवति॥ तद्वांश्च तेन गुप्तत्वाद् ... ॥

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, ...