Shatapatha Brahmana 13.2.1.1

13.2.1.1

prajāpatirdevebhyo yajñānvyādiśat sa ātmannaśvamedhamadhatta te devāḥ prajāpatimabruvanneṣa vai yajño yadaśvamedho'pi no'trāstu bhaga iti tebhya etānannahomānkalpayadyadannahomānjuhoti devāneva tatprīṇāti

Pragâpati assigned the sacrifices to the gods; the Asvamedha he kept for himself. The gods said to him, 'Surely, this--to wit, the Asvamedha--is a sacrifice: let us have a share in that also.' He contrived these Anna-homas (food-oblations) for them: thus when he performs the Annahomas, it is the gods he thereby gratifies.