Verse 1.1.9

तेनेयं त्रयीविद्या वर्तते ओमित्याश्रावयत्योमिति शंसत्योमित्युद्गायत्येतस्यैवाक्षरस्यापचित्यै महिम्ना रसेन ॥ १.१.९ ॥

teneyaṃ trayīvidyā vartate omityāśrāvayatyomiti śaṃsatyomityudgāyatyetasyaivākṣarasyāpacityai mahimnā rasena || 1.1.9 ||

9. With Om one begins the threefold Vedic ritual, and with Om one starts reciting the Vedas. With Om one starts singing the Vedic hymns, and again with Om one sings the udgān [from the Vedas, in praise of Om, or Brahman]. All this is a tribute to Om. Again, all this is possible by virtue of the essence derived from Om [in the form of wheat and other food].

Word-for-word explanation:

Tena, by this [Om]; iyam, this; trayī vidyā vartate, threefold Vedic ritual begins; om iti, with Om; āśrāvayati, the recitation begins; om iti śaṃsati, with Om begins the singing of the hymn; om iti udgāyati, with Om the udgān [the praise to Om] begins; etasya akṣarasya, to this akṣara [Brahman]; eva apacityai, to pay homage; mahimnā, for its greatness; rasena, with the essence [of Om],

Commentary:

To create some interest in Om, it is being praised here.

Om is indispensable even if you are performing a Vedic ritual. You begin reciting a Vedic verse with Om, singing a Vedic hymn with Om, and closing your final udgān with Om. In short, the whole procedure is dedicated to Om. Not only that, those who participate in this ritualistic worship derive their strength and vigour from Om, for the butter or barley syrup they drink as a stimulant is from Om.

How? Om is the medium through which sacrifices are performed, and the effects of the sacrifices are carried to the sun. These then return to the earth as rain. From rain come life and food. Again, because of life and food, a person is able to perform sacrifices.

Thus, it is the essence of Om that makes ritualistic worship, such as sacrifices, possible. Ritualistic worship is therefore a testimony to the greatness of Om. Om is both the cause and the effect.