The works of Ādi Śaṅkarācārya

Viṣṇusahasranāmastotram

Verse 181

ओमित्येकाक्षरं ब्रह्म व्याहरन्मामनुस्मरन् ।यः प्रयाति त्यजन्देहं स याति परमां गतिम् ॥

In plain words

Om — that one syllable is brahman. Whoever sounds it and holds me in mind as he sets out, letting the body go, reaches the highest goal.

Close to the Sanskrit

Uttering the one-syllabled brahman, that is, 'Om', and remembering me — he who goes forth abandoning the body, he goes to the supreme goal.