Thread on “Beef Eating” section from Satapatha 3.1.2.21 (Link:  https://www.wisdomlib.org/hinduism/book/satapatha-brahmana-english/d/doc63182.html#note-e-35100) .

This occurs in context of apsudīkṣa, that prescribes external purificatory rites, leading to final inner purification+

What is the final stage? It is the stage of giving up material desires and engaging in niṣkāma karmās. Hence, the mantras as below.+

sa dhenvai cānaḍuhaśca nāśnīyāddhenvanaḍuhau vā idaṃ sarvam bibhṛtaste devā abruvandhenvanaḍuhau vā idaṃ sarvam bibhṛto hanta yadanyeṣāṃ vayasāṃ vīryaṃ taddhenvanaḍuhayordadhāmeti+

[Let him not eat the cow (Vedas) and bull (Prāṇa), for they support all this (accessories to upāsaṇa). The gods said, “The cow (Vedas) & the bull (Prāṇa) support all this (accessories to upāsaṇa). Let us provide them with the strength of oblations which are of other nature”]+

Brihadāraṇyaka Up. 5.8.1 refers to “Cow” as speech of the form of the 3 Vedas and “Bull” as Prāṇa that accompanies Cow as from prāṇa, vāk is produced. “idaṃ sarvam bibhṛtaste” -  they support all accessories to bhakti yoga like food, cattle, offspring by yielding these.+

If some one wants the Brihadāraṇyaka reference for Cow and Bull, here -  https://www.wisdomlib.org/hinduism/book/the-brihadaranyaka-upanishad/d/doc122195.html. This is Sri Sankara’s Bhāśya, but he agrees with us on this and comments as we do.+

“idaṃ sarvam bibhṛtaste” – Vāk and Prāṇa support all accessories to upāsaṇa like food, cattle, offspring as they yield it by virtue of their karmas.+

“Let us not eat them” – “Eating” means, “using them as we please”. Ie, let us not use them for fruitive works in desire for their fruits. Instead, provide them with the strength of oblations.+

Oblations, Yaga, Homa are called “anyeṣāṃ vayasāṃ” – other nature than speech as they are supported by speech, which is the supporter. The Kāṇva recension reads, “yad anyeṣāṃ vayasāṃ vīryaṃ yad anyeṣām paśūnām” – where “paśūnām” signifies all sacrificial offerings+

The “strength” of oblations is the Jñāna - “all this belongs to Iśa” (īśāvāsyamidaṁ sarvaṁ). One must provide this as support to the Veda, dedicating fruits of Yaga etc to Brahman. niṣkāma karma is recommended+

sa yadanyeṣāṃ vayasāṃ vīryamāsīttaddhenvanaḍuhayoradadhus
vīryamāsīttaddhenvanaḍuhayoradadhustasmāddhenuścaivānaḍvāṃśca bhūyiṣṭham bhuṅktas+

[The Gods bestowed the strength of these oblations that are of other nature to the cow (Vedas) and the bull (Prāṇa). Therefore, the cow (Vedas) and bull (Prāṇa) enjoy Brahman who is bhūma, or abundant.]+

They “enjoy” means they experience being used for the service of Brahman. "bhūyiṣṭham” according to Acharyas signifies “bhūma” -  Brahman who has an abundance of auspicious qualities. Remember bhūma vidyā or meditation on Brahman as the "abundant" in Chāndogya+

Now, the succeeding mantras explain what happens if this is not followed and one uses the Vedas for fruitive works in desire of svarga, bhoga etc.+

taddhaitatsarvāśyamiva yo dhenvanaḍuhayoraśnīyādantagatiriva

[Thus, if one were to eat the cow & bull, ie, engage Vedas & Prāṇa in fruitive works, there will be, as it were, an eating (enjoyment) of everything (experience of all objects of enjoyment) & perishing, as it were]+

“sarvāśyamiva” – The performer of fruitive works attains worlds like svarga and feels, for a while, as though he is experiencing all objects of enjoyment that he ever wanted (signified by “iva”)+

“yādantagatiriva” – However, he is always dwelling on the fact that the period of enjoyment is coming to an end. “antagata” means perishability. “iva” as though it was only a very short time even if it was for thousands of years.+

The idea is, desire can never be satiated and all objects of enjoyment perish. Yayāti mentions this in Adi Parva of MB. Now, the one enjoying bhoga in svarga etc is bound to come down again, as below+

taṃhādbhutamabhijanitorjāyāyai garbhaṃ niravadhīditi papamakaditi pāpī kīrtis

[That person would again be born as one existing in bhogya or sense objects, well-known as a sinner, “he is endlessly seeking the woman’s abode (company)”, “he commits sinful deeds”.]+

“adbhuta” means  -“adyam” is bhogyam -  bhavati – He becomes one associated with sense gratification as his desire is not satiated. Eventually, this leads to krodha, moha etc and he eventually becomes a sinner like rāvaṇa etc.+

tasmāddhenvanaḍuhayornāśnīyāttadu hovāca yājñavalkyo 'śnāmyevāhamaṃsalaṃ cedbhavatīti

[Therefore, let him not eat the cow and bull, ie, engage the Vedas and Prāṇa in fruitive works. Yājñavalkya said, “I indeed eat it, if it is bestowing strength (for upāsaṇa)".]+

Here, a clarification by Yājñavalkya is given. Though performance of fruitive works is discouraged, it is not forbidden if you require food, wealth, offspring etc to sustain your upāsaṇa+

That is to say, one who needs things for the bare minimum of sustaining his life and upāsaṇa, which cannot be done with a weak body, can use the fruits of kāmya karmās. That is what Yājñavalkya says here. "Amshala" means that which imparts strength of Yoga.+

kātyāyaṇa srauta sūtra also defines this section as “dhenvanaḍuhayornāṣrīyāt, puruṣadharmo vā sambhavat amsalabhojanaṃ vā” – Gist: No loss of prosperity, if speech and Prāṇa are to be used as means to Brahman (puruṣa), or for enjoyment of items that strengthen upāsaṇa+

So this section has no mention of eating anything, let alone beef. I came across this section on the web while browsing for something else, so thought of clarifying.//