Bhashya
नित्यान्यधिगतानि कर्माणि उपा- त्तदुरितक्षयार्थानि, काम्यानि च फलार्थिना पूर्वस्मिन्ग्रन्थे ।इदानीं कर्मोपादानहेतुपरिहाराय ब्रह्मविद्या प्रस्तूयते ।कर्महेतु काम स्यात् , प्रवर्तकत्वात् ।आप्तकामाना हि कामा भावे स्वात्मन्यवस्थानात्प्रवृत्त्यनुपपत्ति ।आत्मकामत्वे चाप्त- कामता ।आत्मा च ब्रह्म ।तद्विदो हि परप्राप्ति वक्ष्यति ।अत अविद्यानिवृत्तौ स्वात्मन्यवस्थान परप्राप्ति , 'अभय प्रतिष्ठा विन्दते ' ' एतमानन्दमयमात्मानमुपसङ्क्रामति ' इत्या- दिश्रुते ।काम्यप्रतिषिद्धयोरनारम्भात् आरब्धस्य च उपभो- गेन क्षयात् नित्यानुष्ठानेन च प्रत्यवायाभावात् अयत्नत एव स्वात्मन्यवस्थान मोक्ष ।अथवा, निरतिशयाया प्रीत स्वर्ग- शब्दवाच्याया कर्महेतुत्वात्कर्मभ्य एव मोक्ष इति चेत्, न, कर्मानेकत्वात् ।अनेकानि हि आरब्धफलानि अनारब्धफलानि च अनेकजन्मान्तरकृतानि विरुद्धफलानि कर्माणि सम्भवन्ति ।निषदिति विश्लेष्यते, तत्सेविना गर्भजन्मजरादिनिशातनात् , तदवसादनाद्वा ब्रह्मण उपनिगमयितृत्वात्, उपनिषण्ण वा अस्या पर श्रेय इति ।तदर्थत्वाद्ग्रन्थोऽप्युपनिषत् ॥
In plain words
Obligatory rituals were explained in the previous section as serving to destroy past sins, while desire-driven rites were meant for those seeking specific results. Now, to eliminate the root cause of all action, the knowledge of Brahman is introduced. Desire is the primary cause of action because it instigates activity. For one whose desires are fulfilled, desires cease; resting entirely within the Self, all motivation to act naturally subsides. When the Self is one's sole desire, one is truly fulfilled, and the Self is none other than Brahman. The scripture declares that the knower of Brahman attains the supreme. Therefore, when ignorance is dispelled, abiding in one's own true nature is liberation, as confirmed by Vedic texts like 'He attains the fearless foundation' and 'He reaches this blissful Self.' Since prohibited and optional actions are abandoned, past karma is exhausted through experience, and obligatory duties prevent the accumulation of new demerit, liberation is nothing other than effortless abiding in one's own Self. If someone argues that liberation comes from ritual action because actions produce the supreme happiness called heaven, we say no; for actions are manifold, comprising countless contradictory deeds accumulated across past lives—both active and dormant. The word Upanishad is derived from its power to destroy the miseries of womb-birth, aging, and death for those who practice it, and because it leads the seeker directly to supreme Brahman, wherein ultimate liberation is firmly seated. Because the text serves this exact purpose, it is called the Upanishad.
Close to the Sanskrit
Obligatory duties are attained as serving the purpose of destroying accumulated sins, and desire-based ones for one seeking fruits in the previous text. Now, for the removal of the cause of undertaking action, the knowledge of Brahman is introduced. Desire is the cause of action, because it is an instigator. For fulfilled desires, in the absence of desires, due to resting in one's own self, there is the impossibility of activity. When there is self-desire, there is also the state of fulfilled desires. And the self is Brahman. The scripture will declare the attainment of the supreme for the knower of that. Hence, upon the cessation of ignorance, abiding in one's own self is the attainment of the supreme, according to such Vedic passages as 'He finds fearless foundation,' 'He approaches this Self which consists of bliss.' Since there is no initiation of prohibited and desire-based actions, and due to the exhaustion of commenced action through experience, and due to the absence of demerit through the performance of daily duties, abiding in one's own self effortlessly indeed is liberation. Or if one argues that liberation is from actions alone because actions are the cause of supreme happiness designated by the word heaven, no, because actions are multiple. Indeed, numerous actions done in past lives—commenced and uncommenced fruits, mutually contradictory—are possible. It is analyzed as 'niṣad', because it destroys womb-birth, old age, and other miseries of those who resort to it, or because of causing them to sink, or because it leads the seeker to Brahman, or because supreme welfare is firmly seated in this. Because the text has this purpose, it is also called Upanishad.