ārurukṣor muner yogaḿ
karma kāraṇam ucyate
yogārūḍhasya tasyaiva
śamaḥ kāraṇam ucyate

Translation of Bhagavad Gita 6.3

For one who is a neophyte in the eightfold yoga system, work is said to be the means; and for one who is already elevated in yoga, cessation of all material activities is said to be the means.

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

The process of linking oneself with the Supreme is called yoga. It may be compared to a ladder for attaining the topmost spiritual realization. This ladder begins from the lowest material condition of the living entity and rises up to perfect self-realization in pure spiritual life. According to various elevations, different parts of the ladder are known by different names. But all in all, the complete ladder is called yoga and may be divided into three parts, namely jnana-yoga, dhyana-yoga and bhakti-yoga. The beginning of the ladder is called the yogaruruksu stage, and the highest rung is called yogarudha.

Concerning the eightfold yoga system, attempts in the beginning to enter into meditation through regulative principles of life and practice of different sitting postures (which are more or less bodily exercises) are considered fruitive material activities. All such activities lead to achieving perfect mental equilibrium to control the senses. When one is accomplished in the practice of meditation, he ceases all disturbing mental activities.

A Krishna conscious person, however, is situated from the beginning on the platform of meditation because he always thinks of Krishna. And, being constantly engaged in the service of Krishna, he is considered to have ceased all material activities.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

“But then the practitioner of astanga yoga would have to practice niskama karma yoga for his whole life.”

This verse therefore speaks of the limits of karma yoga. For the practitioner of yoga (muneh), desiring to rise to the stage of steady meditation (yogam), the cause of his elevation is action, karma, because that purifies his heart. For one who has attained steadiness in meditation (yoga arudhasya),   the cause of maintaining that level is cessation (samah) of all actions, which produce agitation. In other words,  the aspirant  for steady meditation does not have complete purity of heart.

Commentary by Sri Ramanuja of Sri Sampradaya:

6.3 Karma Yoga is said to be the means for an aspirant for release who ‘seeks to climb the heights of Yoga,’ i.e., the vision of the self. For the same person, when he has climbed the ‘heights of Yoga,’ i.e., when he is established in Yoga — tranquility, i.e., freedom from actions is said to be the means. A man should perform actions until he has attained release (Moksa) in the form of the vision of the self. Full release comes only with the fall of the body. The ‘vision of the self’ referred to here is called Moksa by courtesy. When does not become established in Yoga? Sri Krsna replies:

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

Does this mean that one must practice karma yoga or prescribed Vedic activities all their life? Apprehending such a question Lord Krishna sets the parameters for it. Karma yoga leads to knowledge because performing Vedic activities purifies the mind. But once the mind has been purified one advances to yoga or the science of the individual consciousness attaining communion with the ultimate consciousness. Then one leaves karma yoga and becomes devoted to meditation, absorbed internally with no inclination for external activities which impedes and distracts introspection and reflection. This is said to be the means for spiritual knowledge to mature.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

The time parameters of karma yoga or performance of prescribed Vedic activities is explained by Lord Krishna in this verse. For the person who seeks fulfilment in the performance of actions, the means to fulfilment is prescribed Vedic activities itself which gives bliss and leads to the final destination of moksa or liberation. It is seen that even those attaining moksa possess equanimity of mind as the resultant fruit. Equanimity is eliminating all things from the mind that are not related to Lord Krishna. Even while experiencing the prarabdha karmas or the consequential reactions from actions, the all comprehensive and conscious presence of equanimity is seen to manifest in some and weathering out the impact one remains fixed on activities pertaining to the Supreme Lord. It has therefore been stated that only those who have perceived the perception of the Supreme Lord experience supreme bliss and will their minds fixed in equanimity. But until the elimination of the prarabdha karmas has come those of superior spiritual intelligence will immerse themselves in sravanam or hearing and kirtanam or reciting the glories of the Supreme Lord Krishna’s transcendental qualities and pastimes.

Now begins the summation.

The comprehensive path for attaining moksa is equanimity of mind. The compound word yoga-arudhasya are those whose continuous meditation bequeaths equanimity. Those of equanimity in mind meditate on the Supreme Lord Krishna or His authorised incarnations as given in the Vedic scriptures while performing all activities. Even from them prescribed Vedic activities must be performed with a totality of being according to individual ability. One’s individual potency determines the ability to complete an activity or not. Those who are able to complete the activity are called qualified. Those who strive to complete the activity but are unable to complete it are called aspirants. One who is benevolent to all beings makes the Supreme Lord pleased and merciful to that one. Such qualified beings place the Supreme Lord Krishna or His Vedically authorised incarnations firmly in the center of their lives through there consciousness, meditation, words, deeds and every action. There is no contrary activity to this for them. By the performance of such action exclusively the Supreme Lord is elated with that person. Serenity, equanimity of mind, self control, austerity, restraint of the senses, rejection of the rewards of action and renunciation are required for aspirants while performing prescribed Vedic activities in their striving for moksa. But it is also seen that the qualified perform prescribed Vedic activities in devotion to the Supreme Lord even after attaining moksa. So following in their wake it is clear that no one is exempt from performing prescribed Vedic activities according to qualification before attaining moksa or after attaining it.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

If the previous verse is true then does one have to perform karma yoga or prescribed Vedic activities until death? Lord Krishna clarifies this with the word aruruksoh meaning who aspires. If one is aspiring for atma tattva or realisation of the soul then karma yoga is merely a stepping stone until one is established in selfless actions without ego influence. Such actions soon lead to renunciation which culminates in dhyana yoga or the science of the individual consciousness attaining communion with the ultimate consciousness by meditation. The purport is that an aspirant should perform prescribed Vedic activities until they are securely established in renunciation which initiates reflection and introspection, culminating in meditation which leads to the attainment of atma tattva.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

6.3 Aruruksoh, for one who wishes to ascend, who has not ascended, i.e. for that very person who is unable to remain established in Dhyana-yoga;-for which person who is desirous to ascend?-munch, for the sage, i.e. for one who has renounced the results of actions;-trying to ascend to what?-yogam, to (Dhyana-) yoga; karma, action; ucyate, is said to be; the karanam, means. Tasya, for that person, again; yoga-arudhasya, when he has ascended to (Dhyana-) yoga; samah, inaction, withdrawl from all actions; eva, alone; ucyate, is said to be; karanam, the means for remaining poised in the state of meditation. This is the meaning. To the extent that one withdraws from actions, the mind of that man who is at cease and self-controlled becomes concentrated. When this occurs, he at once becomes established in Yoga. And accordingly has it been said by Vyasa: ‘For a Brahmana there is no wealth conparable to (the knowledge of) oneness, sameness, truthfulness, character, equipoise, harmlessness, straightforwardness and withdrawal from various actions’ (Mbh. Sa. 175.37). After that, now is being stated when one becomes established in Yoga:

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

6.3 Aruruksoh etc for a sage : For a man of wisdom. Action : that which requires to be performed. Cause (1st) : a means to attain. Quietude : to remain uninterrupted at the stage [already] achieved. Here Cause (2nd) is an indicator. The same idea is made clear as-

Sanskrit Shloka Without Transliteration Marks:

aruruksor muner yogam
karma karanam ucyate
yogarudhasya tasyaiva
samah karanam ucyate

Sanskrit to English Word for Word Meanings:

ārurukṣoḥ — who has just begun yoga; muneḥ — of the sage; yogam — the eightfold yoga system; karma — work; kāraṇam — the means; ucyate — is said to be; yoga — eightfold yoga; ārūḍhasya — of one who has attained; tasya — his; eva — certainly; śamaḥ — cessation of all material activities; kāraṇam — the means; ucyate — is said to be.