स्वभावजेन कौन्तेय निबद्धः स्वेन कर्मणा। कर्तुं नेच्छसि यन्मोहात्करिष्यस्यवशोऽपि तत् ॥

swbhāva-jena kaunteya nibaddhaḥ svena karmaṇā kartuṁ nechchhasi yan mohāt kariṣhyasy avaśho ’pi tat

O son of Kuntî, bound by thine own duty born of thine own nature, that which from delusion thou desirest not to do, even that helplessly thou shalt perform.

In plain words: Krishna, calling Arjuna "son of Kunti" (his mother), says that Arjuna is tied to the duty that comes from his own nature. What he now refuses to do out of confusion, he will end up doing anyway, without choice.