Bg 4.20

tyaktva karma-phalasangam
nitya-trpto nirasrayah
karmany abhipravrtto ’pi
naiva kiñcit karoti sah

Word for word: 
tyaktva — having given up; karma-phala-asangam — attachment for fruitive results; nitya — always; trptah — being satisfied; nirasrayah — without any shelter; karmani — in activity; abhipravrttah — being fully engaged; api — in spite of; na — does not; eva — certainly; kiñcit — anything; karoti — do; sah — he.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Abandoning all attachment to the results of his activities, ever satisfied and independent, he performs no fruitive action, although engaged in all kinds of undertakings.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This freedom from the bondage of actions is possible only in Krishna consciousness, when one is doing everything for Krishna. A Krishna conscious person acts out of pure love for the Supreme Personality of Godhead, and therefore he has no attraction for the results of the action. He is not even attached to his personal maintenance, for everything is left to Krishna. Nor is he anxious to secure things, nor to protect things already in his possession. He does his duty to the best of his ability and leaves everything to Krishna. Such an unattached person is always free from the resultant reactions of good and bad; it is as though he were not doing anything. This is the sign of akarma, or actions without fruitive reactions. Any other action, therefore, devoid of Krishna consciousness, is binding upon the worker, and that is the real aspect of vikarma, as explained hereinbefore.