BG Chap 18 - The opinion of the Lord on tyāga and sannyāsa
The Lord says that one should not give up sacrifice, charity and penance, but should perform them, since they purify even the great souls. They destroy the faults accumulated by repeated births, thru the knowledge arising within them like a lotus blossoming from a root. Even among kāmya karmas, those sacrifices, charities and austerities, which are sāttvika in nature, should be performed.
The mood in which they are performed helps them to purify one’s consciousness. These actions must be done without the misconception of being the doer and thus being attached, and also should be done without longing for results. One should do these actions only with the thought that they are worship of the Lord, since they are the instructions of the Lord. Giving up the idea of being the doer and giving up seeking results is tyāga, and this is also called sannyāsa. This conclusion of the Lord about tyāga is the best, because it includes additionally renunciation of being the doer. Actions need not be given up because by themselves they produce no reactions. They produce reactions only when we think that we are the doer and the fruits are for us to enjoy. Thus the true standard of renunciation is detachment from the fruits of work while performing one’s duty. Any activity which leads to devotional service to the Lord should be accepted. That is the highest criterion of religion. A devotee of the Lord should accept any kind of work, sacrifice or charity which will help him in the discharge of devotional service to the Lord.