अयमात्मा हि ब्रह्मैव सर्वात्मकतया स्थितः ।इति निर्धारितं श्रुत्या बृहदारण्यसंस्थया ॥ ५५ ॥
In plain words
This Self — this very one — is Brahman and nothing else, standing as the self of everything there is. That is the finding of śruti, settled in the Bṛhadāraṇyaka.
Close to the Sanskrit
This Self indeed is Brahman alone, abiding as the self of all; thus it has been determined by the śruti residing in the Bṛhadāraṇyaka.