Śatapatha Brāhmaṇa ("of a hundred paths") 2.6.1.8

2.6.1.8

sa jaghanena gārhapatyam | prācīnāvītī bhūtvā dakṣiṇāsīna etaṃ ṣaṭkapālam puroḍāśaṃ gṛhṇāti sa tata evopotthāyottareṇānvāhāryapacanaṃ dakṣiṇā tiṣṭhannavahanti sakṛtphalīkaroti sakṛdu hyeva parāñcaḥ pitarastasmātsakṛtphalīkaroti

He takes out [the rice for] that cake of six potsherds, while seated behind the Gârhapatya, and looking southwards, with the sacrificial cord over his right shoulder. From thence he rises and threshes (the rice), while standing north of the Dakshina-fire, with his face towards the south. He cleans it but once; since it is once for all that the fathers have departed.