Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 35

Sanskrit:

इत्येष मानवो वंशो यथा सङ्ख्यायते भुवि ।तथा विट्‌शूद्रविप्राणां तास्ता ज्ञेया युगे युगे ॥ ३५ ॥

ITRANS:

ity eṣa mānavo vaṁśoyathā saṅkhyāyate bhuvitathā viṭ-śūdra-viprāṇāṁtās tā jñeyā yuge yuge

Translation:

Thus I have described the royal dynasty of Manu, as it is known on this earth. One can similarly study the history of the vaiśyas, śūdras and brāhmaṇas living in the various ages.

Purport:

Just as the dynasty of kings includes exalted and insignificant, virtuous and wicked monarchs, varieties of human character are found in the intellectual, commercial and laboring orders of society.