Śatapatha Brāhmaṇa ("of a hundred paths") 2.4.3.12

2.4.3.12

atha yadeṣa etena yajate | tannāha nvevaitasya tathā kaścana kṛtyayeva tvadviṣeṇeva tvatpralimpatīti devā akurvanniti tvevaiṣa etatkaroti yamu caiva devā bhāgamakalpayanta tamu caivaibhya eṣa etadbhāgaṃ karotīmā u caivaitadubhayīroṣadhīryāśca manuṣyā upajīvanti yāśca paśavastā anamīvā akilviṣāḥ kurute tā asyānamīvā akilviṣā imāḥ prajā upajīvanti tasmādvā eṣa etena yajate

Now when he performs that sacrifice, he does so either for the reason that no one will then defile (the plants) either by magic or poison; or because the gods did so. And whatever share the gods assigned (to themselves), that share he thereby makes over to them. Moreover, he thereby renders wholesome and faultless both kinds of plants,--those on which men and beasts subsist; and these creatures subsist on those wholesome and faultless (plants) of his: this is why he performs that sacrifice.