Śatapatha Brāhmaṇa ("of a hundred paths") 4.2.4.12

4.2.4.12

tato devāḥ | arcantaḥ śrāmyantaścerusta etadagniṣṭomasadyaṃ dadṛśusta etenāgniṣṭomasadyena sarvaṃ yajñaṃ samavṛñjantāntarāyannasurānyajñāttatho evaiṣa etenāgniṣṭomasadyena sarvaṃ yajñaṃ saṃvṛṅkte 'ntareti sapatnānyajñāttasmādvā agniṣṭomasadbhavati

Then the gods went on singing praises and toiling. They devised this Agnishtoma feast, and by means of this Agnishtoma feast they appropriated the entire sacrifice and excluded the Asuras from the sacrifice. And in like manner does this (sacrificer), by means of this Agnishtoma feast, now appropriate the entire sacrifice, and exclude his enemies from the sacrifice: therefore he celebrates the Agnishtoma.