Bhashya
अविद्याकृतामर्वत्वनिवृत्तिं चेत्सर्वभावापत्तिं ब्रह्मविद्याफलं मन्यसे, ब्रह्मभाविपुरुषकल्पना व्यर्था स्यात् ।प्राग्ब्रह्मविज्ञानादपि सर्वो जन्तुर्ब्रह्मत्वान्नित्यमेव सर्वभावापन्नः परमार्थतः ; अविद्याया तु अब्रह्मत्वमसर्वत्वं चाध्यारोपितम्-यथा शुक्तिकायां रजतम्, व्योम्नि वा तलमलवत्त्वादि ; तथेह ब्रह्मण्यध्यारोपितमविद्यया अब्रह्मत्वमसर्वत्वं च ब्रह्मविद्यया निवर्त्यते-इति मन्यसे यदि, तदा युक्तम्-यत्परमार्थत आ-सीत्परं ब्रह्म, ब्रह्मशब्दस्य मुख्यार्थभूतम् 'ब्रह्म वा इदमग्र आसीत्' इत्यस्मिन्वाक्ये उच्यत इति वक्तुम् ; यथाभूतार्थवादित्वाद्द्वेदस्य ।न त्वियं कल्पना युक्ता-ब्रह्मशब्दार्थविपरीतो ब्रह्मभावी पुरुषो ब्रह्मेत्युच्यत इति, श्रुतहान्यश्रुतकल्पनाया अन्याय्यत्वात्-महत्तरे प्रयोजनान्तरेऽसति अविद्याकृतव्यतिरेकेणाब्रह्मत्वमसर्वत्वं च विद्यत एवेति चेत्, न, तस्य ब्रह्मविद्ययापोहानुपपत्तेः ।न हि कचित्साक्षाद्वस्तुधर्मस्यापोढ्री दृष्टा कर्त्री वा ब्रह्मविद्या, अविद्यायास्तु सर्वत्रैव निवर्तिका दृश्यते ; तथा इहाप्यब्रह्मत्वमसर्वत्वं चाविद्याकृतमेव निवर्त्यतां ब्रह्मविद्यया ; न तु पारमार्थिकं वस्तु कर्तुं निवर्तयितुं वा अर्हति ब्रह्मविद्या ।तस्माद्व्यर्थैव श्रुतहान्यश्रुतकल्पना ॥
In plain words
If you imagine that the fruit of knowing Brahman is the cessation of ignorance-born limitation and the attainment of universal being, then the whole notion of a soul eventually becoming Brahman collapses as redundant. In absolute truth, even before awakening, every living being is already established in that universal state simply because they are intrinsically Brahman. What actually happens is that non-Brahmanhood and limitation are merely superimposed by ignorance—just as silver is projected onto a shell, or flatness and stains onto empty space. Just so, the limitations falsely superimposed upon Brahman by nescience are dispelled by the knowledge of Brahman. If this is your view, it is entirely sound: for the supreme Brahman, which truly existed in the beginning and forms the literal sense of the scriptural declaration 'Brahman indeed was this in the beginning,' is described just as it is, because the Veda speaks the truth of reality. But the notion that a person somehow transforms into Brahman later—contradicting the very definition of the word—is unacceptable, because it discards direct scriptural testimony in favor of an unsupported fiction. If you argue that limitations persist as real features apart from nescience because no greater purpose overrides them, we reply: no, because a real objective trait cannot be eradicated by knowledge. Knowledge is never observed anywhere to act upon or alter the intrinsic nature of a real thing; its sole function everywhere is to dispel ignorance. Therefore, let those limitations born of ignorance be removed here by the knowledge of Brahman, for knowledge has no power to manufacture or destroy actual existence. Hence, any theory that discards direct scripture to invent ungrounded fictions is utterly pointless.
Close to the Sanskrit
If you think the cessation of limitation produced by ignorance and the attainment of all-state is the fruit of the knowledge of brahman, the postulation of a person becoming brahman would be useless. Even prior to the knowledge of brahman, every creature is eternally established in all-state by virtue of being brahman from the absolute standpoint; but non-brahmanhood and non-allness are superimposed by ignorance—just as silver on mother-of-pearl or flatness and dirtiness etc., on empty space; similarly, non-brahmanhood and non-allness superimposed on brahman here by ignorance are removed by the knowledge of brahman—if you think thus, then it is proper to assert that the supreme brahman, which existed in absolute truth and was the primary meaning of the word 'brahman', is spoken of in the scriptural sentence 'Brahman indeed was this in the beginning', because the Veda states things as they are. This imagination is not proper—that a person who becomes brahman, contrary to the meaning of the word 'brahman', is called brahman—because of the impropriety of abandoning what is heard and imagining what is unheard. If it is argued that apart from the distinction made by ignorance, non-brahmanhood and non-allness actually exist when there is no other greater purpose, no, because it is impossible for them to be removed by the knowledge of brahman. For the knowledge of brahman is never seen anywhere as a doer or a remover of an intrinsic property of a real object; but knowledge is seen everywhere as the remover of ignorance. Therefore, let non-brahmanhood and non-allness, which are produced by ignorance, be removed here by the knowledge of brahman; the knowledge of brahman is not fit to make or remove a real existent object. Therefore, the postulation that abandons the heard and imagines the unheard is entirely useless.