Śatapatha Brāhmaṇa ("of a hundred paths") 2.6.1.16

2.6.1.16

sa dakṣiṇaiva paridhīnparidadhāti | dakṣiṇā prastaraṃ stṛṇāti nāntardadhāti vidhṛtī sakṛdu hyeva parāñcaḥ pitarastasmānnāntardadhāti vidhṛtī

He lays the enclosing-sticks along (the fire, with their tops) towards the south; and the prastara also he spreads (with the grass-tops) towards the south; nor does he lay down the two vidhritis between (the barhis and the prastara). Once for all the fathers have departed from hence: therefore he lays no vidhritis between.