B.G 3.14, 15 and 16

annād bhavanti bhūtāni parjanyādannasambhavaḥ। yajñād bhavati parjanyō yajñaḥ karmasamudbhavaḥ ॥14॥

karma brahmodbhavaṁ viddhi brahmākṣarasamudbhavam। tasmāt sarvagataṁ brahma nityaṁ yajñe pratiṣṭhitam ॥15॥

ēvaṁ pravartitaṁ cakraṁ nānuvartayatīha yaḥ। aghāyuriṁdriyārāmō mōghaṁ pārtha sa jīvati ॥16॥

From food comes beings, and food becomes possible from rains. The rains are produced from 'Yajna' and it is 'Yajna' that is the source of the prescribed duties. The actions have their origin in Brahman, and understand that the Vedas also arose simultaneously from that same Brahman. Therefore, the all pervading Brahman is always situated in the 'Yajna'. O Partha, he who does not adhere to the cycle thus set in motion, who only delights in the senses, is sinful, and lives in vain.

Gīta Tātparya 3.14 to 16

Elaboration of the Yajna cycle with the usage of 'Akshara' to mean Vēdas is quoted as a testimonial from Narada Purana. Thus, 'Brahma' means the Brahman, and 'Akshara' means the Vēdas. This interpretation also ensures it is coherent with the prase "tasmāt sarvagataṁ brahma", i.e. "the all pervading Brahma".

jananāt parasasyādēḥ parjanyō mēghasantatiḥ। sa yajñāt karmaṇaḥ sōpi samastaṁ karma kēśavāt॥

sa nityō'pyakṣaratatirūpādvākyādidha gamyatē। vākyamuccāryatē bhūtaiḥ tānyannāt tacca mēghataḥ॥

tasmāt sarvagatō viṣṇuḥ nityaṁ yajñē pratiṣṭhitaḥ। ēvaṁ pravartitaṁ cakraṁ nānuvartayatīha yaḥ। sa pāpō viśvahantr̥tvāt narakē majjati dhruvam॥

The vegetation is born from the continuous series of clouds through rain. Similarly, from that lord Keshava, through 'Yajna', all duties are performed. Even though He is eternal, he is understood through the statements in the form of 'akshara' i.e. Vēdas, by the utterances of those sentences by beings, the way food is produced from the clouds. Therefore, the all pervading lord Vishnu is eternally established in 'Yajna'. That sinner who does not adhere to the cycle thus set is motion, because of being the destroyer of the world, certainly sinks to hell.

vācikō mānasō yajñō nyāsināṁ tu viśēṣataḥ। vanasthasyākratuḥ yajñaḥ kratvādirgrahiṇōkhilaḥ॥

śuśrūṣādyātmakō yajñō vihitō brahmacāriṇaḥ। vidyābhayādidānaṁ ca sarvēṣāmapi sammatam॥

gr̥hiṇō vittadānaṁ tu vanasthasyānnapūrvakam। sarvaiḥ kāryaṁ tapō ghōramiti sarvē trikarmiṇaḥ॥

iti nāradīyē।

The sacrifice of speech and mind is meant especially for the renounced order. The forest dwellers, i.e. who are retired, should keep their sacrifices light by offering food that involved no killing. Serving others by physical service is the sacrifice recommended for celibate students. Studies and other such activities are the agreeable sacrifice to all. House holder must give wealth as charity and the retired person by offering food first. All must practice penance. Thus, three orders, i.e. student, householder, and retired, must sacrifice through studies, charity, and penance.

- states Naradiya Purana

brahmākṣaraśabdārthayōḥ vyatyāsē tasmāt sarvagataṁ brahmēti pratyabhijñāvirōdhaḥ cakrapravēśaśca ॥14-16॥

The meaning of the words 'Brahma' and 'Akshara' must be differentiated, with 'Brahma' to mean the Omnipresent lord, and the other to mean that (Vedas) which provides entry into the cycle (of Yajna). Thus, it becomes coherent with the phrase "tasmāt sarvagataṁ brahma", i.e. "the all pervading Brahma".