Karmaphala Sannyasa is detachment from and abandonment of the fruits of action. The phrase is derived from the Sanskrit words karma (action), phala (fruit) and sannyasa (renunciation).
The fruits of actions may be ishta (pleasant), anishta (unpleasant), or misra (mixed). The Bhagavad Gita uses both karmphala tyaga and karma sannyasa (IV.11-13) to mean performance of action without the desire for the fruits of work and without attachment. One who does the prescribed work, renouncing the fruit, is also known as karmaphala tyagi (renouncer of the fruits of action).
According to Kaivalya Upanishad, immortality is attained neither by work nor by progeny, but by renunciation. In Brihadaranyaka Upanishad, the true knowers of atman renounce the desire for progeny, wealth, and worlds, and wander about as mendicants.
The expression karmaphala sannyasa is a call for pure action. Action is pure when it is free from ego-sense and performed without attachment, affection or disregard and not benefit motivated. Karma yoga is ideal performance of actions in a detached spirit without caring for their fruits (nishkamakarma).
Disinterested action is not abstention from action (naishkarmya) or negation of action, but performance of action in a detached spirit. It is not renunciation of action, but renunciation in action. Such action is desireless, dispassionate, and dedicated to the divine. It is service because there is renunciation of self interest, desire and attachment (Bhagavad Gita II. 47; XIV.2). In this sense every work is transformed into an offering to God, and such work is the highest form of sacrifice (Bhagavad Gita XII.2).