Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 13
Sanskrit:
विप्रक्षत्रियविट्शूद्रा मुखबाहूरुपादजा: ।वैराजात् पुरुषाज्जाता य आत्माचारलक्षणा: ॥ १३ ॥
ITRANS:
vipra-kṣatriya-viṭ-śūdrāmukha-bāhūru-pāda-jāḥvairājāt puruṣāj jātāya ātmācāra-lakṣaṇāḥ
Translation:
In Tretā-yuga the four social orders were manifested from the universal form of the Personality of Godhead. The brāhmaṇas appeared from the Lord’s face, the kṣatriyas from the Lord’s arms, the vaiśyas from the Lord’s thighs and the śūdras from the legs of that mighty form. Each social division was recognized by its particular duties and behavior.