Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.3.8

2.5.3.8

athāha somāyānubrūhīti | saumyamājyabhāgaṃ sa uttarasyaudanasya sarpirāsecanāccaturājyasyāvadāyātikrāmatyatikramyāśrāvyāha somaṃ yajeti vaṣaṭkṛte juhoti

He then says, 'Pronounce the invitatory prayer to Soma!' with reference to Soma's butter-portion. He then takes four cuttings of butter from the hollow of the northern pap, and steps over. Having stepped over and called for the 'Sraushat,' he says, 'Pronounce the offering-prayer to Soma!' and pours out the oblation, as soon as the Vashat has been uttered.