The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Verse 267

सा होवाच मैत्रेयीत्रैव मा भगवान्मो- हान्तमापीपिपन्न वा अहममं विजाना- मीति स होवाच न वा अरेऽहं मोहं ब्र- वीम्यविनाशी वा अरेऽयमात्मानुच्छि- त्तिधर्मा ॥ १४ ॥

In plain words

Maitreyī said: 'Right here is where you've lost me completely, venerable one — I don't understand this Self at all.' He said: 'I'm not speaking confusion. This Self, truly, cannot be destroyed — it simply does not come to an end.'

Close to the Sanskrit

She, Maitreyī, said: 'Just here, venerable sir, you have plunged me into the depth of confusion; I do not understand this [Self].' He said: 'I do not, indeed, speak confusion, O one; this Self, indeed, O one, is imperishable, of a nature that knows no cessation.'