Śatapatha Brāhmaṇa ("of a hundred paths") 4.1.4.1

4.1.4.1

kratūdakṣau ha vā asya mitrāvaruṇau | etannvadhyātmaṃ sa yadeva manasā kāmayata idam me syādidaṃ kurvīyeti sa eva kraturatha yadasmai tatsamṛdhyate sa dakṣo mitra eva kraturvaruṇo dakṣo brahmaiva mitraḥ kṣatraṃ varuṇo 'bhigantaiva brahma kartā kṣatriyaḥ

Mitra and Varuna, forsooth, are his intelligence and will; and as such belonging to his self: whenever he desires anything in his mind, as 'Would that this were mine! I might do this!' that is intelligence; and whenever that is accomplished, that is will. Now intelligence indeed is Mitra, and will is Varuna; and Mitra is the priesthood, and Varuna the nobility; and the priesthood is the conceiver, and the noble is the doer.