etanme samshayam krishna chhettumarhasyasheshataha |
tvadanyaha samshayasyaasya chhettaa na hyupapadyate || 39 ||

To dispel this doubt of mine, O Krishna, only you are worthy. For, other than you, no one is fit to dispel this doubt.
etat : this
me : my
samshayam : doubt
krishna : O Krishna
chhettum : dispel
arhasi : you are worthy
asheshataha : completely
tvadanyaha : other than you
samshayasyaasya : of this doubt
chhettaa : one who can dispel
na : none
hi : for
upapadyate : is fit
Arjuna offers one last point in his question to Shri Krishna with regards to the promise of meditation. Earlier, Arjuna wanted to know the fate of the seeker who strives hard but does not reach the state of the perfected meditator before he dies. He then added an illustration of the cloud that is helplessly scattered by winds, comparing it to a seeker who achiever neither spiritual nor material success. Arjuna makes a final point in this question by reminding Shri Krishna that only he can answer this question.
By now, Arjuna had come to the conclusion that Shri Krishna was something more than his friend and charioteer. In some shlokas, Shri Krishna even referred to himself as Ishvara. Only one who is beyond the material world can answer a question that transcends the material world, and that is Ishvara himself. Therefore, Arjuna found it fit to ask such a question to Shri Krishna.
The answer to this question is given by Shri Krishna in the upcoming shlokas. These shlokas comprise the final portion of the sixth chapter.