Bhagavad Gita 18.44

कृषिगौरक्ष्यवाणिज्यं वैश्यकर्म स्वभावजम् |
परिचर्यात्मकं कर्म शूद्रस्यापि स्वभावजम्

Translation

Agriculture, dairy farming, and commerce are the natural works for those with the qualities of Vaishyas. Serving through work is the natural duty for those with the qualities of Shudras.