Shatapatha Brahmana 9.1.1.10

9.1.1.10

pariśritsu juhoti | lomāni vai pariśrito na vai lomasu viṣaṃ na kiṃ cana hinastyuttarārdhe 'gnerudaṅ tiṣṭhanjuhotyetasyāṃ ha diśyetasya devasya gṛhāḥ svāyāmevainametaddiśi prīṇāti svāyāṃ diśyavayajate

He offers on (three) enclosing-stones, for the enclosing-stones are the hair, and neither poison nor anything else injures one at the hair. He offers whilst standing on the left (north) side of Agni (the altar), with his face to the north; for in that region lies the house of that god: it is thus in his own region that he gratifies him, in his own region he contents him with offering.