yuktah karma-phalam tyaktva
shantim apnoti naisthikim
phale sakto nibadhyate
The steadily devoted soul attains unadulterated peace because he offers the result of all activities to Me; whereas a person who is not in union with the Divine, who is greedy for the fruits of his labor, becomes entangled.
Commentary by Srila Prabhupada
The difference between a person in Krishna consciousness and a person in bodily consciousness is that the former is attached to Krishna whereas the latter is attached to the results of his activities. The person who is attached to Krishna and works for Him only is certainly a liberated person, and he has no anxiety over the results of his work. In the Bhagavatam, the cause of anxiety over the result of an activity is explained as being one’s functioning in the conception of duality, that is, without knowledge of the Absolute Truth. Krishna is the Supreme Absolute Truth, the Personality of Godhead. In Krishna consciousness, there is no duality. All that exists is a product of Krishna’s energy, and Krishna is all good. Therefore, activities in Krishna consciousness are on the absolute plane; they are transcendental and have no material effect. One is therefore filled with peace in Krishna consciousness. But one who is entangled in profit calculation for sense gratification cannot have that peace. This is the secret of Krishna consciousness—realization that there is no existence besides Krishna is the platform of peace and fearlessness.
Commentary by Sri Visvanatha Cakravarti Thakur
Performing action with no attachment leads to liberation and performing action with attachment leads to bondage. The performer of karma yoga (yuktah) attains steady peace (naistikim santim). This means he attains liberation. The karmi with desires (ayuktah), attached to the results, due to performing actions out of lust (kama karena) becomes bound.