Bhagavatapurana 6.1.41

6.1.41

yena svadhāmny amī bhāvā rajaḥsattvatamomayāḥ /
guṇanāmakriyārūpairvibhāvyante yathātatham //

41. It is the Almighty Lord by whom and on whose power stand supported all these beings that are dominated by Rajas, Satva, and Tamas and observed to be severally characterised by (different) qualities, names (as Brahmana, Kshatriya, and so on), duties(as the study of Veda and the like) and forms or social distinctions (as Varna and Asrama).