Śatapatha Brāhmaṇa ("of a hundred paths") 13.1.5.3

13.1.5.3

yadubhau rājanyau apāsmādbrahmavarcasaṃ krāmetkṣatrasya vā etadrūpaṃ yadrājanyo na vai kṣatre brahmavarcasaṃ ramata iti brāhmaṇo'nyo gāyati rājanyo'nyo brahma vai brāhmaṇaḥ kṣatraṃ rājanyastadasya brahmaṇā ca kṣatreṇa cobhayataḥ śrīḥ parigṛhītā bhavati

‘And were both to be Râganyas (nobles), spiritual lustre would depart from him; for he--to wit, the Râganya--is a form of noble rank, and spiritual lustre takes no delight in noble rank.' One of those who sing is a Brâhmana, and the other a Râganya; for the Brâhmana means priestly office, and the Râganya noble rank: thus his distinction (social position) comes to be guarded on either side by the priesthood and the nobility.