Bhashya
अत्र तु परमात्मलोकमग्नौ ब्राह्मणे चेच्छन्तीति केचित् ।तदसत्, अविद्याधिकारे कर्माधिकारार्थं वर्णविभागस्य प्र-स्तुतत्वात्, परेण च विशेषणात् ; यदि ह्यत्र लोकशब्देनधीतः कर्माद्यवबोधकत्वेन न भुनक्ति, अन्यद्वा लौकिकं कृ-ष्यादि कर्म अकृतं स्वात्मना अनभिव्यञ्जितम् आत्मीयफ-लप्रदानेन न भुनक्ति, एवमात्मा स्वो लोकः स्वेनैव नित्या-त्मस्वरूपेणानभिव्यञ्जितः अविद्याप्रहाणेन न भुनक्त्येव ।ननु किं स्वलोकदर्शननिमित्तपरिपालनेन? कर्मणः फलप्रा-प्तिध्रौव्यात् इष्टफलनिमित्तस्य च कर्मणो बाहुल्यात् तन्निमि-त्तं पालनमक्षयं भविष्यति-तन्न, कृतस्य क्षयवत्त्वादित्येतदा-ह-यत् इह वै संसारे अद्भुतवत् कश्चिन्महात्मापि अनेवं-वित् स्वं लोकं यथोक्तेन विधिना अविद्वान् महत् बहु अश्व-मेधादि पुण्यं कर्म इष्टफलमेव नैरन्तर्येण करोति-अनेनैवा-नन्त्यं मम भविष्यतीति, तत्कर्म ह अस्य अविद्यावतःअविद्याजनितकामहेतुत्वान्न स्वप्रदर्शनविभ्रमोद्भूतविभूतवन्अन्ततः अन्ते फलोपभोगस्य क्षीयत एव ; तत्कारणयोर्वि-द्याकामयोश्चलत्वात् कृतक्षयध्रौव्योपपत्तिः ।तस्मान्न पुण्य-कर्मफलपालनानन्त्याशा अस्त्येव ।अत आत्मानमेव स्वं लो-कम्-आत्मानमिति स्वं लोकमित्यस्मिन्नर्थे, स्वं लोकमितिप्रकृतत्वात् इह च स्वशब्दस्याप्रयोगात्-उपासीत ।स यआत्मानमेव लोकमुपास्ते-तस्य किमित्युच्यते-न हास्य कर्मक्षीयते, कर्माभावादेव-इति नित्यानुवादः ; यथा अविदुषः
In plain words
Some argue that the 'world of the Supreme Self' refers to the sacrificial fire or the Brahmana. But this is incorrect. The division of social classes is introduced solely to establish eligibility for ritual action within the realm of ignorance, and the text explicitly qualifies this world as 'supreme'. If the word 'world' here meant something that does not sustain us because it merely reveals ritual actions, or if unperformed worldly actions like agriculture failed to sustain us because they remain unmanifested and cannot yield their fruits, then the Self—which is our true world—would indeed fail to sustain us if it remained unmanifested through our failure to destroy ignorance. One might ask: 'Why not simply rely on the preservation of our world through ritual actions? Since the fruits of rituals are guaranteed and such actions are abundant, will not the preservation they bring be everlasting?' No, because whatever is produced by action is inherently perishable. As the text says: 'If anyone in this transmigratory world, even a great soul, without this knowledge, performs vast and meritorious rituals like the horse-sacrifice continuously, thinking "This will bring me eternity," that action of his, born of ignorance and driven by desire, eventually wears out when its fruits are exhausted. It is not like the self-luminous glory of the Self. Since both ritual action and desire are unstable, whatever they produce must inevitably perish. Therefore, there is no hope of finding eternal security in the fruits of meritorious deeds. One must meditate on the Self alone as one's true world. He who meditates on the Self as his world finds that his work is never exhausted—not because his rituals last forever, but because he has transcended the very need for ritual action. This is a statement of eternal truth, unlike the state of the ignorant.
Close to the Sanskrit
But here, some desire the world of the Supreme Self in the fire or in the Brahmana. That is incorrect, because the division of classes is introduced for the purpose of eligibility for action in the sphere of ignorance, and because of the qualification by 'supreme'. If indeed here by the word 'world' that which is grasped does not protect by being the revealer of action etc., or other worldly action like agriculture, unperformed, does not protect by its own nature being unmanifested by giving its own fruit, in this way the Self, one's own world, unmanifested by its own eternal Self-nature, does not protect indeed by the destruction of ignorance. But is it not by the preservation caused by the vision of one's own world? Since the attainment of the fruit of action is certain, and because action which is the cause of desired fruit is abundant, the preservation caused by that will be imperishable—that is not so, because what is made is perishable, thus he says: 'that which here indeed in transmigratory existence, like a wonder, even some great soul, not knowing thus, ignorant of his own world according to the stated rule, performs great, abundant, meritorious action like the Ashvamedha, with desired fruit indeed, continuously—thinking "by this indeed endlessness will be mine", that action of his, who is ignorant, because of having desire produced by ignorance as its cause, not like the glory arisen from the delusion of self-revelation, in the end, at the end of the enjoyment of the fruit, is indeed exhausted; because of the instability of its two causes, knowledge and desire, the correctness of the certainty of the destruction of what is made is established. Therefore, there is indeed no hope of endlessness of the preservation of the fruit of meritorious action. Therefore, one should worship the Self indeed as one's own world—"the Self" in this sense of "one's own world", because "one's own world" is the topic, and here because of the non-use of the word "sva"—one should worship. He who worships the Self indeed as the world—what is said for him?—"his action is not exhausted", because of the very absence of action—thus it is a constant restatement; as of the ignorant.'