Shatapatha Brahmana 9.1.2.11

9.1.2.11

bāhyenāgniṃ harati | ime vai lokā eṣo 'gnirebhyastallokebhyo bahirdhā śucaṃ dadhāti bahirvedīyaṃ vai vedirasyai tadbahirdhā śucaṃ dadhāti

Outside the fire-altar he throws it; for this fire-altar indeed is the same as these (three) worlds: he thus puts pain outside these worlds;--outside the sacrificial ground (vedi); for the Vedi is this (earth): he thus puts pain outside this earth.