Bhagavad Gita 8.13

ओमित्येकाक्षरं ब्रह्म व्याहर्न्मानुस्मरण |
यः प्रयति त्यजन्देहं स याति परमं गतिम्

Translation

One who departs from the body while remembering Me, the Supreme Personality, and chanting the syllable Om, will attain the supreme goal.