Śatapatha Brāhmaṇa ("of a hundred paths") 9.4.3.5

9.4.3.5

sa yadimāṃlokampṛṇayaiva cinoti kṣatraṃ vai lokampṛṇā kṣatraṃ tadviśyattāraṃ dadhātyubhayāṃścinotyadhvarasya cāgneścādhvarasya pūrvānathāgnestasyokto bandhuryaṃ-yamevādhvaradhiṣṇyaṃ nivapati taṃ-taṃ cinotyāgnīdhrīyam prathamaṃ cinoti taṃ hi prathamaṃ nivapati dakṣiṇata udaṅṅāsīnastasyokto bandhuḥ

And when he builds up these (hearths) only with the space-filling one, the Lokamprinâ being the nobility --he thereby places the chieftain, as the eater, among the clan. He builds up (dhishnya-hearths) both of the Soma-sacrifice, and of the fire-altar; first those of the Soma-sacrifice, and then those of the fire-altar: the significance of this has been explained. Whatever Soma-hearth he (merely) throws up (at the Soma-sacrifice), that he (now) builds up. The Âgnîdhrîya he builds first, for that one he throws up first (at the Soma-sacrifice); (he does so) whilst sitting to the right (south) of it: the significance of this has been explained.