Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.4.21

3.3.4.21

atha pratiprasthātā | agreṇa śālāmagnīṣomīyeṇa paśunā pratyupatiṣṭhate 'gnīṣomau vā etamantarjambha ādadhāte yo dīkṣata āgnāvaiṣṇavaṃ hyado dīkṣaṇīyaṃ havirbhavati yo vai viṣṇuḥ somaḥ sa havirvā eṣa bhavati yo dīkṣate tadenamantarjambha ādadhāte tatpaśunātmānaṃ niṣkrīṇīte

Thereupon the Pratiprasthâtri steps up to the front of the hall with the victim for Agni and Soma. Now Agni and Soma have seized him, who consecrates himself, between their jaws, for that consecration-offering above belongs to Agni and Vishnu, and Vishnu, forsooth, is no other than Soma, and the offering is he himself who is consecrated: thus they have seized him between their jaws; and by this victim he now redeems himself.