Matsyapurana 4.28

4.28

vāmadevastu bhagavān asṛjanmukhato dvijān
rājanyān asṛjadbāhvor viṭchūdrān ūrupādayoḥ //

“The Mânasa sons of Brahmâ—Marîchi, &c.—who were born first, began to pass their days in the terrestrial globe in the practice of asceticism. The Creator, marking the indifference of His Mânasa sons with regard to the work of creation, produced Vâmadeva, the wielder of the trident and also Sanatkumar, the first even of the first borns.”—26-27. “From the mouth of Lord Vâmadeva came forth the Brâhmaṇas, from His arms the Kṣatriyas, from His thighs the Vaiśyas, and from His feet the Śûdras.”—28.