Verse 2.18-21

Verse 2.18: “These perishable bodies are said to belong to that eternal body-owner, the indestructible one that passes comprehension. Therefore, do fight, O Scion of Bharata.

Verse 2.19: “He who understands him as the slayer, and he who deems him as the slain: both these do not truly know. This one slays. not, nor is slain.

Verse 2.20: “He is not born, nor does he at any time die: nor, having once ‘been’, is he once again not going to ‘be.’ Unborn, eternal, everlasting and primeval is he: he is not destroyed when the body comes to be destroyed.

Verse 2.21: “Who-so realises him as the indestructible, eternal, unborn, and immutable: how and whom can such a person, O son of Pritha, cause to be slain, or slay? (136)

Commentary called Jnaneshwari by Jnaneshwar:

Everything that has taken a body-form and shape is naturally perishable and therefore you should face fighting. With your self-conceit fastened on the body and fixing your erroneous gaze on the body, you are the slave of the belief that you are the slayer while the Kauravas are the slain. You do not realise the essential truth. Were you to consider carefully (you will realise) that neither you are the slayer, nor they the slain. Just as in a dream you feel the dream all real, but when you awake and look out, you find nothing; in the same way being the victim of delusion and Maya you are enmeshed in this error for nothing. Just see that striking at the shadow with a weapon does not cause hurt to the body; or that the disappearance of the Sun’s reflection from an overturned pitcher full of water does not make the Sun himself to disappear along with the reflection, or that the interior of any finite thing gives form to infinite space, but merges into general space (Akash [ākāśa]—Sky) as soon as the finite thing tumbles down; even so although the body gets destroyed is the soul indestructible and therefore, O Arjuna, be not under any illusion like that.