Jnana Yoga-Bhagavad Gita Chapter 4 [Approaching the Ultimate Truth]
Krishna Said > Shaloka: 19
One is understood to be in full knowledge whose every act is devoid of desire for sense gratification. He is said by sages to be a worker whose fruitive action is burned up by the fire of perfect knowledge.
Only a person in full knowledge can understand the activities of a person in Krishna consciousness. Because the person in Krishna consciousness is devoid of all kinds of sense-gratificatory propensities, it is to be understood that he has burned up the reactions of his work by perfect knowledge of his constitutional position as the eternal servitor of the Supreme Personality of Godhead. He is actually learned who has attained to such perfection of knowledge. Development of this knowledge of the eternal servitorship of the Lord is compared to fire. Such a fire, once kindled, can burn up all kinds of reactions to work.