The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Verse 33

स वै नैव रेमे तस्मादेकाकी न रमते

In plain words

He found no delight whatsoever, and therefore anyone who is entirely alone does not find joy.

Close to the Sanskrit

He indeed did not delight at all; therefore one alone does not take delight.