Shatapatha Brahmana 5.5.4.21

5.5.4.21

dvāvagnī uddharanti | uttaravedāvevottaramuddhate dakṣiṇaṃ netsomāhutīśca surāhutīśca saha juhavāmeti tasmāddvāvagnī uddharantyuttaravedāvevottaramuddhate dakṣiṇamatha yadā vapābhiḥ pracaratyathaitayā parisrutā pracarati

They take up two fires; on the northern altar (they lay down) the northern (fire), and on a raised (mound) the southern one, thinking, 'Lest we should offer together the Soma-libations, and the Surâ (liquor) -libations:' therefore they take up two fires, and on the northern altar (they lay down) the northern (fire), and on a raised (mound) the southern one. And when he proceeds with the omenta, then he proceeds with that spirituous liquor.