Bhagavad Gita 18.44
कृषिगौरक्ष्यवाणिज्यं वैश्यकर्म स्वभावजम्। परिचर्यात्मकं कर्म शूद्रस्यापि स्वभावजम्।।18.44।।
kṛṣigaurakṣyavāṇijyaṃ vaiśyakarma svabhāvajam| paricaryātmakaṃ karma śūdrasyāpi svabhāvajam||18.44||
krishigaurakshyavanijyam vaishyakarma svabhavajam paricaryatmakam karma shudrasyapi svabhavajam18.44
Meaning
Agriculture, cattle-rearing, and trade are the natural duties of the Vaishya. Service is the natural duty of the Shudra. Each serves society through their natural capacity.
कृषि, गौपालन तथा वाणिज्य — ये वैश्य के स्वाभाविक कर्म हैं, और शूद्र का स्वाभाविक कर्म है परिचर्या अर्थात् सेवा करना।
This is verse 44 of 78 in Chapter 18 (Moksha Sannyasa Yoga) of the Bhagavad Gita.