yuktaḥ karma-phalaḿ tyaktvā
śāntim āpnoti naiṣṭhikīm
ayuktaḥ kāma-kāreṇa
phale sakto nibadhyate

Translation of Bhagavad Gita 5.12

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 Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

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 Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

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.

Commentary by Sri Ramanuja of Sri Sampradaya:

5.12 A Yogin is one who has no hankering for fruits other than the self, and who is exclusively devoted to the self. If a man renounces the fruits of actions and performs actions merely for the purification of himself, he attains lasting peace, i.e., he attains bliss which is of the form of lasting experience of the self. The unsteady person is one who is inclined towards fruits other than the self. He has turned himself away from the vision of the self. Being impelled by desire, he becomes attached to fruits of actions, and remains bound for ever by them. That is, he becomes a perpetual Samsarin or one involved in transmigratory cycle endlessly. What is said is this: Free of attachment for fruits and attributing one’s actions to Prakrti which has developed into the form of senses, one should perform actions merely to free the self from bondage. Next, the shifting of agency to Prakrti, from which the body has come into existence, is described:

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

How is it to be understood that performing the same actions some people are bound to material existence and others are released from material existence? The answer to this question is specifically being addressed by Lord Krishna. One who is equiposed and unmotivated by material desires of rewards is never bound by material nature; but the craving reward seeker obsessed with desire birth after birth is never released from material existence.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

For emphasising the qualifications of observing equanimity the merits and demerits are reiterated by Lord Krishna. The word yuktah meaning communion infers equanimity with a sense of renunciation.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

Attachment to the rewards to be gained from one’s actions is the root cause for bondage to the perpetual cycle of birth and death in material existence. Lord Krishna presents this assertion with positive and negative examples. The aspirant for atma tattva or realisation of the soul who unmotivated by desires offers all actions unto the Supreme Lord attains moksa or liberation and everlasting peace. Whereas the person who performs actions never offering them to the supreme is contaminated with the blemish of selfish motives and the craving of rewards and is unable to relinquish the conception of ego and proprietorship thinking that they are the body and miserably failing by such mentality are bound tightly in material existence.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

5.12 Tyaktva, giving up; karma-phalam, the result of work; yuktah, by becoming resolute in faith, by having this conviction thus-‘Actions are for God, not for my gain’; apnoti, attains; santim, Peace, called Liberation; naisthikim arising from steadfastness. It is to be understood that he attains this through the stages of purification of the heart, acquisition of Knowledge, renunciation of all actions, and steadfastness in Knowledge. On the other hand, however, he who is ayuktah, lacking in resolute faith; he, phale saktah, being attached to result; thinking, ‘I am doing this work for my gain’; kama-karena, under the impulsion of desire-kara is the same as karana (action); the action of desire (kama-kara; under that impulsion of desire, i.e. being prompted by desire; nibadhyate, gets bound. Therefore you become resolute in faith. This is the idea. But one who has experienced the supreme Reality-

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

5.12 Yuktah etc. Highest : that from which there is no return.

Sanskrit Shloka Without Transliteration Marks:

yuktah karma-phalam tyaktva
santim apnoti naisthikim
ayuktah kama-karena
phale sakto nibadhyate

Sanskrit to English Word for Word Meanings:

yuktaḥ — one who is engaged in devotional service; karma-phalam — the results of all activities; tyaktvā — giving up; śāntim — perfect peace; āpnoti — achieves; naiṣṭhikīm — unflinching; ayuktaḥ — one who is not in Kṛṣṇa consciousness; kāma-kāreṇa — for enjoying the result of work; phale — in the result; saktaḥ — attached; nibadhyate — becomes entangled.