यद्यदाचरति श्रेष्ठस्तत्तदेवेतरो जनः।
स यत्प्रमाणं कुरुते लोकस्तदनुवर्तते।।3.21।।
।।3.21।। श्रेष्ठ पुरुष जैसा आचरण करता है अन्य लोग भी वैसा ही अनुकरण करते हैं वह पुरुष जो कुछ प्रमाण कर देता है लोग भी उसका अनुसरण करते हैं।।
So understanding that the whole Earth benefits from the performance of prescribed Vedic activities, one should act altruistically not for themselves but for the welfare of the world. This is the meaning Lord Krishna is conveying. The word sresthah means great personality expert in the conclusions of the Vedas. Whatever actions such a great person performs others will try to follow. It may be that a certain activity should be performed on a special day. The common people will wait to see how a great person takes the initiative on such an action and then they will follow suit. Hence the great personalities should always act in an exemplary manner to set the standard for the world. In this way they inspire everyone to perform prescribed Vedic actions according to the qualification of ones varna or caste in life and ones asrama or stage in life. If one fails to do this by neglect or omission one commits sin by omitting to help benefit the welfare of the world by their example and the consequence will be one will fall down from the path they achieved after many lifetimes.