Chapter VIII · Śloka 13
ओमित्येकाक्षरं ब्रह्म व्याहरन्मामनुस्मरन् ।
यः प्रयाति त्यजन्देहं स याति परमां गतिम् ॥
om ity ekākṣaraṃ brahma vyāharan mām anusmaran |
yaḥ prayāti tyajan dehaṃ sa yāti paramāṃ gatim ||
Whoever departs leaving the body, uttering the single syllable Oṃ — Brahman — and remembering Me, reaches the highest goal.
The monosyllable Oṃ is the sonic body of Brahman; uttering it with genuine remembrance of the Supreme at death is the culminating act of an entire life of yoga, securing the highest liberation.