Śatapatha Brāhmaṇa ("of a hundred paths") 13.4.2.13

13.4.2.13

tasyai saptadaśaiva sāmidhenyo bhavanti rayimantāvājyabhāgau vīryaṃ vai rayivīryasyāptyai vīryasyāvaruddhyā ā viśvadevaṃ satpatiṃ na pramiye saviturdaivyasya tadityupāṃśu haviṣo yājyānuvākye nitye saṃyājye nedyajñapathādayānīti kLpta eva yajñe'ntataḥ pratitiṣṭhati triṣṭubhau bhavata indre vai vīryaṃ triṣṭubindriyasyaiva vīryasyāvaruddhyai hiraṇyaṃ dakṣiṇā suvarṇaṃ śatamānaṃ tasyoktam brāhmaṇam

For this (ishti) there are again seventeen kindling-verses. The two butter-portions are possessed of 'wealth,' with a view to his obtaining and securing vigour, for wealth is vigour (strength). [The verses, Rig-veda V, 82, 7; IV, 54, 4,] 'The all-divine, true lord (we hope to gain this day by our hymns, Savitri of true impulsion),' and 'Indestructible is that (work) of the divine Savitri, (that he will ever sustain the whole world: whatever he, the fair-fingered, bringeth forth over the extent of the earth and the expanse of the sky, that is truly his own),' pronounced in a low voice, are the invitatory and offering formulas of the chief offering. Those of the Svishtakrit (he makes) the regular ones, thinking, 'Lest I should depart from the path of sacrifice:' he thus finally establishes himself in the well-ordered sacrifice. Trishtubh-verses they are for the sake of his gaining and securing (Indra's) energy, vigour, for the Trishtubh is the vigour in Indra. The priests’ fee is gold weighing a hundred (grains): the meaning of this has been explained.