om ity etad akṣaram udgītham upāsīta | om iti hy udgāyati | tasyopavyākhyānam
Let a man meditate on the syllable Om, called the udgîtha; for the udgîtha (a portion of the Sâma-veda) is sung, beginning with Om. The full account, however, of Om is this:—
The essence of all beings is the earth, the essence of the earth is water, the essence of water the plants, the essence of plants man, the essence of man speech, the essence of speech the Rig-veda, the essence of the Rig-veda the Sâma-veda, the essence of the Sâma-veda the udgîtha (which is Om).
tad vā etad anujñākṣaram | yad dhi kiṃcānujānāty om ity eva tad āha | eṣo eva samṛddhir yad anujñā | samardhayitā ha vai kāmānāṃ bhavati ya etad evaṃ vidvān akṣaram udgītham upāste
That syllable is a syllable of permission, for whenever we permit anything, we say Om, yes. Now permission is gratification. He who knowing this meditates on the syllable (Om), the udgîtha, becomes indeed a gratifier of desires.
teneyaṃ trayī vidyā vartate | om ity āśrāvayati | om iti śaṃsati | om ity udgāyati | etasyaiva akṣarasyāpacityai mahimnā rasena
By that syllable does the threefold knowledge (the sacrifice, more particularly the Soma-sacrifice, as founded on the three Vedas) proceed. When the Adhvaryu priest gives an order, he says Om. When the Hotri priest recites, he says Om. When the Udgâtri priest sings, he says Om, —all for the glory of that syllable. The threefold knowledge (the sacrifice) proceeds by the greatness of that syllable (the vital breaths), and by its essence (the oblations).
तेनोभौ कुरुतः । यश् चैतद् एवं वेद यश् च न वेद । नाना तु विद्या चाविद्या च । यद् एव विद्यया करोति श्रद्धयोपनिषदा तद् एव वीर्यवत्तरं भवतीति खल्व् एतस्यैवाक्षरस्योपव्याख्यानं भवति
tenobhau kurutaḥ | yaś caitad evaṃ veda yaś ca na veda | nānā tu vidyā cāvidyā ca | yad eva vidyayā karoti śraddhayopaniṣadā tad eva vīryavattaraṃ bhavatīti khalv etasyaivākṣarasyopavyākhyānaṃ bhavati
Now therefore it would seem to follow, that both he who knows this (the true meaning of the syllable Om), and he who does not, perform the same sacrifice. But this is not so, for knowledge and ignorance are different. The sacrifice which a man performs with knowledge, faith, and the Upanishad is more powerful. This is the full account of the syllable Om.