Śatapatha Brāhmaṇa ("of a hundred paths") 4.4.1.18

4.4.1.18

sa yatprātaḥsavana upāvartsyat | gāyatraṃ vai prātaḥsavanam brahma gāyatrī brāhmaṇeṣu ha paśavo 'bhaviṣyannatha yanmādhyandine savana upāvartsyadaindraṃ vai mādhyandinaṃ savanaṃ kṣatramindraḥ kṣatriyeṣu ha paśavo 'bhaviṣyannatha yattṛtīyasavana upāvartata vaiśvadevaṃ vai tṛtīyasavanaṃ sarvamidaṃ viśve devāstasmādime sarvatraiva paśavaḥ

Now, had he returned at the morning pressing--the morning pressing belonging to the Gâyatrî, and the Gâyatrî being the priesthood --then cattle would have come to be with priests only. And had he returned at the midday pressing--the midday pressing belonging to Indra, and Indra being the nobility--cattle would have come to be with nobles only. But in that he returned at the evening pressing--the evening pressing belonging to the All-gods, and the All-gods being everything here--therefore there are cattle everywhere here.