Shatapatha Brahmana 1.6.1.12

1.6.1.12

sa yadyenānpurastāt | asurarakṣasānyāsisaṃkṣannagnireva tānyapāhanrakṣohā rakṣasāmapahantā yadi madhyata āsisaṃkṣannagnireva tānyapāhanrakṣohā rakṣasāmapahantā yadi paścādāsisaṃkṣannagnireva tānyapāhanrakṣohā rakṣasāmapahantāta evaṃ sarvato 'gnibhirgupyamānāḥ svargaṃ lokaṃ samāśnuvata

And if the Asuras and Rakshas wished to attack them in front, Agni repelled them, as the Rakshas-killer, the repeller of the Rakshas; if they wished to attack in the centre, Agni repelled them, as the Rakshas-killer, the repeller of the Rakshas; and if they wished to attack in the rear, Agni repelled them, as the Rakshas-killer, the repeller of the Rakshas: being thus guarded on all sides by Agnis, they reached the world of heaven.