The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Verse 274

तद्वै तदेतदेव तदास सत्यमेव स योहैतं महद्यक्षं प्रथमजं वेद सत्यं ब्रह्मेतिजयतीमाँल्लोकाञ्जित इन्न्वसावसद्य एव-मेतन्महद्यक्षं प्रथमजं वेद सत्यं ब्रह्मेतिसत्यं ५ ह्येव ब्रह्म ॥ १ ॥

In plain words

In the beginning there was only this — pure existence, nothing standing outside it. Whoever knows this vast, radiant, first-born reality under its true name, 'Truth is Brahman,' wins these worlds outright. Could such a person ever be the one who loses? Never — because truth, and truth alone, is Brahman.

Close to the Sanskrit

That, verily, was this very thing; that alone was Truth (Being) at the beginning. He who thus knows this great, wondrous, first-born being as 'Truth is Brahman' conquers these worlds. Would he — the one who thus knows this great, first-born being as 'Truth is Brahman' — be the one defeated? For truth alone, indeed, is Brahman.