Krishna puts the question directly to Arjuna. If you truly know the soul to be indestructible, eternal, unborn, and imperishable — then tell me, Partha: whom exactly do you kill? Whom do you cause to be killed? The question is rhetorical. The answer is: no one. Killing and being killed are events of the body. The soul stands outside them entirely.
This is not a licence for violence. Krishna is not saying 'do whatever you want because it does not matter.' He is saying that Arjuna's specific fear — that fighting will destroy his loved ones — is based on identifying the person with the body. Once that identification is corrected, the fear dissolves. Duty remains; paralysis does not.
The word 'veda' here means not just intellectual knowledge but deep, lived understanding. A person can read about the soul's immortality in a hundred books and still grieve at a funeral. True knowing — the kind Krishna points to — changes how a person sees every event, including death.