2.39 This, which has been taught to thee, is wisdon concerning Sankhya. Now listen to wisdom concerning Yoga, endowed with which, O Arjuna, thou shalt cast off the bonds of action.

2.39 Esa te etc. And this knowledge in th form of determination has been declared [to you] for your sankhya, i.e., perfect knowledge. Now, how the self-same determinate knowledge is also taught for the Yoga i.e., dexerity in action - in that manner only you must listen to by means of which determinate knowledge you shall avoid the binding nature of the actions. Truely, the actions do not themselves bind as they are insentient. Hence, it is the Self which binds Itself by means of the actions in the form of mental impressions.

2.39. O Partha! This equanimous intellect was imparted to you earlier in the path of knowledge (Sankhya Yoga). Now, hear of it in the context of the path of selfless action (Karma Yoga). Endowed with this equanimous intellect, you shall cast off the bondage of action. Commentary: The word 'tu' (now) here is used to distinguish the context of the topics, meaning the topic of Sankhya has been stated earlier, and now the topic of Yoga is being stated. The word 'esha' (this) here refers to the equanimous intellect described in the previous verse. This equanimous intellect was described in detail earlier in Sankhya Yoga (from the eleventh to the thirtieth verse). When there is precise discrimination between the body and the dweller in the body, one experiences one's own self-established state in equanimity. This is because inequality arises only due to attachment to the body. Thus, the description of equanimous intellect is already complete in Sankhya Yoga. Now, hear of this very equanimous intellect in the context of Karma Yoga. The implication of saying 'imam' (this) is that this equanimous intellect is now to be described in the context of Karma Yoga: how is this equanimous intellect attained in Karma Yoga? What is its nature? What is its glory? For these points, the Lord has asked to hear of this intellect in the context of Yoga. "Endowed with which intellect, O Partha, you shall cast off the bondage of action" – In Arjuna's mind, there was the apprehension of incurring sin by fighting (1.36, 45). However, according to the Lord's view, sin is incurred only due to an unequal intellect (attachment and aversion) in actions. With an equanimous intellect, sin is not incurred at all. For example, in the world, many sinful and virtuous activities keep occurring, yet we do not incur sin or virtue from them; because we maintain equanimity towards them, meaning we have no partiality, insistence, attachment, or aversion towards them. Similarly, if you remain endowed with equanimous intellect, these actions will not become binding for you either. In the seventh verse of this very chapter, Arjuna had asked about his welfare. Therefore, the Lord describes the primary means of welfare. First, by explaining the means of Sankhya Yoga, the Lord strongly emphasized performing dutiful action, stating that for a Kshatriya, there is no greater means of welfare than a war that is righteous (2.31). Then He said that if war is fought with equanimous intellect, no sin is incurred (2.38). Now, that same equanimous intellect is being spoken of in the context of Karma Yoga. A Karma Yogi performs all actions for the welfare of the world – "You should also perform action for the sake of engaging the world" (Gita 3.20). By performing action for the welfare of the world, i.e., with a selfless motive to preserve the righteous order of the world, to turn people away from the wrong path and engage them on the right path, the attainment of equanimity becomes easy. With the attainment of equanimity, the Karma Yogi easily becomes free from the bondage of action. This (thirty-ninth) verse fits perfectly after the thirtieth verse; and it should have been placed there. The reason is that this verse describes two disciplines. First, from the eleventh to the thirtieth verse, the discipline (equanimity) through Sankhya Yoga was explained, and now the discipline (equanimity) through Karma Yoga is being explained. Therefore, placing the eight verses from the thirty-first to the thirty-eighth here seems incongruous. Nevertheless, the reason for placing these eight verses here is that before speaking of equanimity in Karma Yoga, it is necessary to describe what is duty and what is not duty. For Arjuna, fighting the war is duty and not fighting is not duty – it is essential to describe this subject. Hence, the Lord spoke the aforementioned eight verses (2.31-38) precisely to describe duty and non-duty, and then spoke of equanimity. The essence is that first, from the eleventh to the thirtieth verse, equanimity was explained through the description of the eternal and the non-eternal – that the eternal is eternal only and the non-eternal is non-eternal only. No one can alter this in any way. Then, from the thirty-first to the thirty-eighth verse, by speaking of duty and non-duty, and from the thirty-ninth verse onwards, the description of equanimity in success and failure of actions and in attainment and non-attainment of results, while renouncing non-duty and adhering to duty, is given.