Mahabharata 13.35.7

न शौद्रं कर्म कर्तव्यं ब्राह्मणेन विपश्चिताशौद्रं हि कुर्वतः कर्म धर्मः समुपरुध्यते

na śaudraṃ karma kartavyaṃ brāhmaṇena vipaścitāśaudraṃ hi kurvataḥ karma dharmaḥ samuparudhyate

Our plain-language meaning of this verse is waiting for scholar review.