Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 21
Sanskrit:
कृषिवाणिज्यगोरक्षा कुसीदं तूर्यमुच्यते । वार्ता चतुर्विधा तत्र वयं गोवृत्तयोऽनिशम् ॥ २१ ॥
ITRANS:
kṛṣi-vāṇijya-go-rakṣākusīdaṁ tūryam ucyatevārtā catur-vidhā tatravayaṁ go-vṛttayo ’niśam
Translation:
The occupational duties of the vaiśya are conceived in four divisions: farming, commerce, cow protection and moneylending. Out of these, we as a community are always engaged in cow protection.