Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.2.36

2.5.2.36

athaitābhyām payasyābhyām pracariṣyantau vipariharataḥ | sa yo meṣo bhavati mārutyāṃ taṃ vāruṇyāmavadadhāti yā meṣī bhavati vāruṇyāṃ tām mārutyāmavadadhāti tadyadevaṃ vipariharataḥ kṣatraṃ vai varuṇo vīryam pumānvīryamevaitatkṣatre dhatto 'vīryā vai strī viśo marutastadavīryāmevaitadviśaṃ kurutastasmādevaṃ vipariharataḥ

Thereupon, being about to proceed with those two oblations of curds, (the Adhvaryu and Pratiprasthâtri) exchange (the ram and ewe): the ram which was on the Maruts' (dish of curds) he (the Adhvaryu) places on that of Varuna; and the ewe which was on Varuna's (dish of curds) he (the Pratiprasthâtri) places on that of the Maruts. Now the reason why they make this exchange, is this,--Varuna is the nobility, and the male represents energy: hence they thereby bestow energy on the nobility. The female, on the other hand, is without energy; and the Maruts are the people: hence they thereby cause the people to be without energy. This is why they make this exchange.