Śatapatha Brāhmaṇa ("of a hundred paths") 4.2.1.15

4.2.1.15

tau jaghanenāhavanīyamaratnī saṃdhattaḥ | tā uttaravedau sādayato dakṣiṇāyāmeva śroṇāvadhvaryuḥ sādayatyuttarāyām pratiprasthātānanusṛjantāvevānādhṛṣṭāsīti tadrakṣobhirevaitaduttaravedimanādhṛṣṭāṃ kuruto viparyeṣyantau vā etāvagnim bhavato 'tyeṣyantau tasmā evaitannihnuvāte tatho hainau vipariyantāvagnirna hinasti

Behind the Âhavanîya fire they put their (right) elbows together, and deposit (the cups) on the high altar: the Adhvaryu on the right hip, and the Pratiprasthâtri on the left--without quitting their hold of them--with 'Unassailable art thou!' whereby they make the high altar unassailable by evil spirits; for they are about, in walking round it, to pass by the fire: hereby, then, they propitiate it, and so the fire does not injure them, while they walk round it on different sides.