Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.1.10

2.3.1.10

dvayaṃ vā idaṃ jīvanam | mūli caivāmūlaṃ ca tadubhayaṃ devānāṃ sanmanuṣyā upajīvanti paśavo mūlā oṣadhayo mūlinyaste paśavo mūlā oṣadhīrmūlinīrjagdhvāpaḥ pītvā tata eṣa rasaḥ sambhavati

That which affords (the means of) subsistence is of two kinds; namely, either rooted or rootless. On both of these, which belong to the gods, men subsist. Now cattle are rootless and plants are rooted. From the rootless cattle eating the rooted plants and drinking water, that juice is produced.