Śatapatha Brāhmaṇa ("of a hundred paths") 1.5.2.4

1.5.2.4

yā vai prajā yajñe 'nanvābhaktāḥ | parābhūtā vai tā evamevaitadyā imāḥ prajā aparābhūtatstā yajña ābhajati manuṣyānanu paśavo devānanu vayāṃsyoṣadhayo vanaspatayo yadidaṃ kiñcaivamu tatsarvaṃ yajña ābhaktam

For, indeed, the creatures that are not allowed to take part in the sacrifice are forlorn; and therefore he makes those creatures here on earth that are not forlorn, take part in the sacrifice: behind the men are the beasts, and behind the gods are the birds, the plants, and the trees; and thus all that here exists is made to take part in the sacrifice.