Śatapatha Brāhmaṇa ("of a hundred paths") 13.2.9.8

13.2.9.8

yaddhariṇo yavamattīti viḍvai yavo rāṣṭraṃ hariṇo viśameva rāṣṭrāyādyāṃ karoti tasmādrāṣṭro viśamatti na puṣṭam paśu manyata iti tasmādrājā paśūnna puṣyati śūdrā yadaryajārā na poṣāya na dhanāyatīti tasmādvaiśīputraṃ nābhiṣiñcati

[The chamberlain addresses the king's fourth wife, Vâg. S. XXIII, 30,] 'When the deer eats the corn,'--the grain (growing in the field), doubtless, is the people, and the deer is royal power: he thus makes the people to be food for the royal power, whence the wielder of royal power feeds on the people;--'it thinks not of the fat cattle,'--whence the king does not rear cattle;--'when the Sûdra woman is the Arya's mistress, he seeks not riches that he may thrive,'--hence he does not anoint the son of a Vaisya woman.