Śatapatha Brāhmaṇa ("of a hundred paths") 2.6.1.43

2.6.1.43

te sarva eva yajñopavītino bhūtvā | anuyājābhyām pracariṣyanta itthādyajamānaśca brahmā ca paścātparītaḥ purastādagnīdupaviśati hotā hotṛṣadane

Being now about to proceed with the after-offerings, they all invest themselves sacrificially (by shifting the cord over to the left shoulder); and thus (invested) the Sacrificer and Brahman walk round to the west, and the Âgnîdhra to the east, side; and the Hotri sits down on the Hotri's seat.