Shatapatha Brahmana 11.1.3.4

11.1.3.4

sa yatpaurṇamāseneṣṭvā indrāya vimṛdhe'nunirvapati sendro me yajño'saditi sarvo vai yajña indrasyaiva sa yatsarvo yajña indrasyaivaiteno hāsyetatsendraṃ havirbhavatyetena sendro yajñaḥ

When, after performing the Full-moon sacrifice, he prepares an additional (cake) for Indra Vimridh, he does so in order that his sacrifice should become shared in by Indra, for every sacrifice belongs to Indra. But inasmuch as every sacrifice belongs to Indra, thereby that oblation of his, and that sacrifice, is already shared in by Indra.