Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 41
Sanskrit:
विप्रो मुखाद् ब्रह्म च यस्य गुह्यंराजन्य आसीद् भुजयोर्बलं च ।ऊर्वोर्विडोजोऽङ्घ्रिरवेदशूद्रौप्रसीदतां न: स महाविभूति: ॥ ४१ ॥
ITRANS:
vipro mukhād brahma ca yasya guhyaṁrājanya āsīd bhujayor balaṁ caūrvor viḍ ojo ’ṅghrir aveda-śūdrauprasīdatāṁ naḥ sa mahā-vibhūtiḥ
Translation:
The brāhmaṇas and Vedic knowledge come from the mouth of the Supreme Personality of Godhead, the kṣatriyas and bodily strength come from His arms, the vaiśyas and their expert knowledge in productivity and wealth come from His thighs, and the śūdras, who are outside of Vedic knowledge, come from His feet. May that Supreme Personality of Godhead, who is full in prowess, be pleased with us.