Link:- The Lord, in the next two verses, authorizes Arjuna to be guided by even-mindedness, already mentioned in the preceding verse and he describes its glory.
esa te'bhihita saitkhye buddhiryoge tvimam srnu
buddhya yukto yaya partha karmabandham prahasyasi
O Purtha (Arjuna), this attitude of mind has been presented to you from the point of view of Jaunayoga (Discipline of Knowledge); now hear of the same, from the point of view of Karmayoga (the Discipline of Selfless-Action). Equipped with this state of mind, you will be able to completely shake off the shackles of Karma (Action). 39
Ea te'bhihita sunkhye buddhiryoge tvimam srnu:-Here the word Tu' (indeed) has been used to show that the description of the Discipline of Action, is different from the Discipline of Knowledge.
The term 'Esa has been used for equanimity, which has been described in the preceding verse and which has already been explained in the Discipline of Knowledge, (from the eleventh to the thirtieth verses). When a man discriminates between the body and the soul, he gets established in equanimity automatically because it is attachment to the body which is an obstacle in the way of equanimity. So this ideal of equanimity has already been presented from the point of view of 'Sankhyayoga (Discipline of Knowledge); now listen to a discourse on equanimity in the context of 'Kamsayoga' (Discipline of Action).
'Imam' (this) term has been used to explain how this equanimity is attained by the Discipline of Action and what its importance is?
Buddhya yukto yayu purtha karmabandham prahasyasi:-Arjuna was afraid of the sin that would accrue by waging the war (1/36, 45). But Lord Krsna says that sin does not accrue by waging the war as it is your duty, but it accrues by having attachment and aversion. So if you attain equanimity, no sin will accrue and your duty of waging the war, will not lead you to bondage.
In the seventh verse of this chapter Arjuna asked Lord Krsna to advise him what was good for him. Hence, Lord Krsna answers his query. First, He mentioned the means of Sankhyayoga (Discipline of Knowledge), and then laid great stress on performance of duty, and told him that there was nothing more welcome to a Ksatriya, than a righteous war (2/31). Then, He told him that no sin would accrue, if he had equanimity ( 2/38). Now, He explains the same equanimity, in the context of 'Karmayoga (Discipline of Action).