Śatapatha Brāhmaṇa ("of a hundred paths") 7.4.1.37

7.4.1.37

kārṣmaryamayīṃ dakṣiṇata upadadhāti | etadvai devā abibhayuryadvai no yajñaṃ dakṣiṇato rakṣāṃsi nāṣṭrā na hanyuriti ta etaṃ rakṣohaṇaṃ vanaspatimapaśyankārṣmaryaṃ ta etena vanaspatinā dakṣiṇato rakṣāṃsi nāṣṭrā apahatyābhaye 'nāṣṭra etaṃ yajñamatanvata tathaivaitadyajamāna etena vanaspatinā dakṣiṇato rakṣāṃsi nāṣṭrā apahatyābhaye 'nāṣṭra etaṃ yajñaṃ tanuta ājyena pūrṇā bhavati vajro vā ājyaṃ vajreṇaivaitaddakṣiṇato rakṣāṃsi nāṣṭrā apahanti

On the right (south) side he lays down one of kârshmarya (gmelina arborea) wood. For at that time the gods were afraid lest the Rakshas, the fiends, should destroy their sacrifice from the south. They saw that Rakshas-killing tree, the Kârshmarya: having by that tree repelled the Rakshas, the fiends, on the south, they spread that sacrifice in a place free from danger and devilry. And in like manner the Sacrificer, having by that tree repelled the Rakshas, the fiends, on the south, now spreads that sacrifice in a place free from danger and devilry. It (the spoon) is filled with ghee;--the ghee is a thunderbolt: it is by the thunderbolt he thus repels the Rakshas, the fiends, on the south.