PRAŚNA UPANISHAD · 5.7

ऋग्भिरेतं यजुर्भिरन्तरिक्षं
सामभिर्यत् तत् कवयो वेदयन्ते ।
तमोङ्कारेणैवायतनेनान्वेति विद्वान्
यत्तच्छान्तमजरममृतमभयं परं चेति ॥ ५.७॥

ṛgbhiretaṃ yajurbhirantarikṣaṃ
sāmabhiryat tat kavayo vedayante ।
tamoṅkāreṇaivāyatanenānveti vidvān
yattacchāntamajaramamṛtamabhayaṃ paraṃ ceti ॥ 5.7॥

“‘To the earth the Rigveda leadeth, to the skies the Yajur, but the Sama to That of which the sages know. Thither the wise man by resting on OM the syllable attaineth, even to that Supreme Quietude where age is not and fear is cast out by immortality.’ ”

Sri Aurobindo · CWSA 18, pp. 189, 190