Bhashya
अन्नं ब्रह्म, अन्नम् अद्यते यन् तत् ब्रह्मेत्येक आचार्या आहुः ; तत् न तथा ग्रहीतव्यम् अन्नं ब्रह्मेति ।अन्ये चाहुः— प्राणो ब्रह्मेति ; तच्च तथा न ग्रहीतव्यम् ।किमर्थं पुनः अन्नं ब्रह्मेति न ग्राह्यम् ? यस्मात् पूयति क्लिश्यते पूतिभावमापद्यते ऋते प्राणात्, तत्कथं ब्रह्म भवितुमर्हति ; ब्रह्म हि नाम तत्, यदविनाशि ।अस्तु तर्हि प्राणो ब्रह्म ; नैवम् ; यस्मात् शुष्यति वै प्राणः शोषमुपैति ऋते अन्नात् ; अत्ता हि प्राणः ; अतः अन्नेन आद्येन विना न शक्नोति आत्मानं धारयितुम् ; तस्मात् शुष्यति वै प्राणः ऋतेऽन्नात् ; अतः एकैकस्य ब्रह्मता नोपपद्यते यस्मात्, तस्मात् एते ह तु एव अन्नप्राणदेवते एकधाभूयम् एकधाभावं भूत्वा गत्वा परमतां परमत्वं गच्छतः ब्रह्मत्वं प्राप्नुतः ।तदेतत् एवमध्यवस्य ह स्म आह— स्म प्रातृदो नाम पितरमात्मनः ; किंस्वित् स्विदिति वितर्के ; यथा मया ब्रह्म परिकल्पितम्, एवं विदुषे किंस्वित् साधु कुर्याम्, साधु शोभनं पूजाम्, कां तु अस्मै पूजां कुर्यामित्यभिप्रायः ; किमेव अस्मै विदुषे असाधु कुर्याम्, कृतकृत्योऽसौ इत्यभिप्रायः ।अन्नप्राणौ सहभूतौ ब्रह्मेति विद्वान् नासौ असाधुकरणेन खण्डितो भवति, नापि साधु-संगच्छन्त एव, श्रेष्ठभावाय च अस्मै कल्पन्ते समर्थ्यन्ते ;साम्नः सायुज्यमित्यादि पूर्ववत् ॥
In plain words
'Food is Brahman,' some teachers say — meaning, whatever you eat as food, that itself is Brahman. But that is not the right way to take it. Others say instead, 'breath is Brahman' — and that misses the mark too. Why does 'food is Brahman' fail? Because food rots, spoils, falls apart the moment breath leaves it — and nothing that decays like that could ever be Brahman, since Brahman, by definition, never perishes. Then perhaps breath alone is Brahman? No, that fails as well — because breath withers and runs dry without food to feed it; breath is only ever the eater, and without something to eat it cannot even sustain itself. So neither one, taken alone, can be Brahman. Only when these two — food and breath — come together as one, reaching their highest, truest state as a pair, do they become Brahman. Having worked this out, the tradition remembers the sage Prātṛda saying to his own father — using 'what, indeed' as a word of open wonder — 'Since I have understood Brahman this way, what good could I possibly do for someone who knows it? What honor, what offering would even be fitting?' And in the same breath: 'Or what harm could I possibly do him? He has already accomplished everything there is to accomplish.' Whoever knows food and breath together as Brahman cannot be diminished by any wrong done to him, and cannot be improved by any kindness either — every such act only ends up confirming the greatness he already has. Union with the Sāman, and everything that follows it, works exactly as it did before.
Close to the Sanskrit
Food is Brahman: 'that which is eaten as food, that is Brahman' — thus some teachers say. That is not to be understood in that way, [namely] 'food is Brahman.' And others say, 'the breath is Brahman'; that too is not to be understood in that way. Why, again, is 'food is Brahman' not to be accepted? Because it rots, deteriorates, falls into a state of putrescence without breath — how, then, can that be fit to be Brahman? For Brahman indeed is that which is imperishable. Let it be, then, that breath is Brahman. Not so either. Because breath indeed withers, comes to exhaustion, without food; for breath is the eater; therefore, without food as sustenance, it is not able to sustain itself; therefore breath indeed withers without food. Hence, since Brahman-hood does not hold for each one separately, therefore these two deities, food and breath, having become one, having reached supremacy, the highest state, together attain Brahman-hood. Having thus determined this, it is remembered that Prātṛda said to his own father — 'kiṃsvit,' 'svit' being a particle of doubt: since Brahman has thus been conceived by me, what good deed, then, might I do for such a knower — what fitting, excellent homage might I offer him? — that is the intent; or, what wrong might I even do to this knower, since he has accomplished all there is to accomplish? — that is the intent. The knower of 'food and breath, existing together, are Brahman' is not diminished by the doing of a wrong deed, nor is he benefited by a good deed either; and [such deeds] only serve, only confirm, his supreme excellence. 'Union with the Sāman' and so on, as before.