YV 6.1j

The new and full moon and the four monthly sacrifices are the beginning of the sacrifice, these Vyahrtis are the Brahman; verily at the beginning of the sacrifice he makes the Brahman. When the year is completed, he should thus with them (Vyahrtis) set down (the oblations), and so with the Brahman he surrounds the year on both sides. To the kingly class falls the blessing of the part of the sacrifice which is performed with the Saman [3]; to the people (falls) the blessing of what (is performed) with the Rc; now the Brahman sacrifices with an offering without a blessing; when he is about to recite the kindling-verses he should first insert the Vyahrtis; verily he makes the Brahman the commencement, and thus the Brahman sacrifices with an offering which has a blessing. If he desire of a sacrificer, 'May the blessing of his sacrifice fall to his foe', he should insert for him those Vyahrtis in the Puronuvakya (verse); the Puronuvakya has the foe for its divinity; verily the blessing of his sacrifice falls to his foe [4]. If he desire of sacrificers, 'May the blessing of the sacrifice fall to them equally', he should place for them one of the Vyahrtis at the half-verse of the Puronuvakya, one before the Yajya, and one at the half-verse of the Yajya, and thus the blessing of the sacrifice falls to them equally. Even as Parjanya rains down good rain, so the sacrifice rains for the sacrificer; they surround the water with a mound, the sacrificer surrounds the sacrifice with a blessing. 'Thou art mind derived from Prajapati [5], with mind and true existence do thou enter me', he says; mind is derived from Prajapati, the sacrifice is derived from Prajapati; verily he confers upon himself mind and the sacrifice. 'Thou art speech, derived from Indra, destroying the foe; do thou enter me with speech, with power', he says; speech is derived from Indra; verily he confers upon himself speech as connected with Indra.