By the scripture 'sacrifice is Viṣṇu' (Taittirīya Saṃhitā 1.7.4), sacrifice is the Lord; action done for His sake is action for the sake of sacrifice. Apart from such action, by other action, this world, the doer of action eligible for it, is bound, has action for its bondage; but not when the action is for the sake of sacrifice. Therefore, O son of Kuntī, perform action for that purpose, for the sake of sacrifice, freed of attachment, free of attachment to the fruit of action. And here is a further reason why the eligible person should do action.
Contemporary English rendering of the Sanskrit bhāṣya, pending scholar review.