यद्दृष्ट्वा नापरं दृश्यं यद्भूत्वा न पुनर्भवः ।यज्ज्ञात्वा नापरं ज्ञेयं तद्ब्रह्मेत्यवधारयेत् ॥ ५५ ॥
In plain words
Once you have seen it, nothing is left to see. Once you have become it, there is no being born again. Once you have known it, nothing is left to know. That — settle it firmly — is Brahman.
Close to the Sanskrit
That which, having been seen, there is nothing further to be seen; that which, having been become, there is no becoming again; that which, having been known, there is nothing further to be known — that one should ascertain as Brahman.