The works of Ādi Śaṅkarācārya

Muṇḍakopaniṣadbhāṣyam

Verse 22

ब्रह्मैवेदममृतं पुरस्ता- ब्रह्म पश्चाद्ब्रह्म दक्षिणतश्चोत्तरेण ।अधश्चोर्ध्वं च प्रसृतं ब्रह्मैवेदं विश्वमिदं वरिष्ठम् ॥ १२ ॥

In plain words

This immortal Brahman alone is in front, Brahman behind, Brahman to the right and to the north, below and above. This entire universe is spread out as Brahman alone; it is the supreme reality.

Close to the Sanskrit

Brahman alone is this immortal [reality] before, Brahman behind, Brahman to the right and by the north, and below and above; extended is Brahman alone, this universe is this greatest.