It is a good policy to behave towards one in the same way he behaves towards another. One who behaves deceitfully should be served deceitfully; and one who behaves honestly should be served with honesty.
यस्मिन् यथा वर्तते यो मनुष्यस्तस्मिंस्तथा वर्तितव्यं स धर्मः। मायाचारो मायया वर्तितव्यः साध्वाचारः साधुना, प्रत्युपेयः॥