Shatapatha Brahmana 2.6.1.31

2.6.1.31

sa upastṛṇīta ājyam | athāsya puroḍāśasyāvadyati sa tenaiva saha dhānānāṃ tena saha manthasya tatsakṛdavadadhātyathopariṣṭāddvirājyasyābhighārayati na pratyanaktyavadānāni nātikrāmatīta evopotthāyāśrāvyāhāgniṃ kavyavāhanaṃ yajeti vaṣaṭkṛte juhoti

He makes an under-layer of butter (in the offering-spoon); then cuts a piece from (the front part of) the cake, and therewith some of the parched grain and the porridge; puts down all this at the same time; and makes two sprinklings of butter thereon. The (places from which he has made the) cuttings he does not replenish with butter, nor does he walk across; but having stepped up (to the fire) on the same side (where he was seated), and called for the 'Sraushat,' he says, 'Pronounce the offering-prayer to Agni Kavyavâhana!' and pours out the oblation, as soon as the Vashat has been uttered.