Bhagavad Gita, Chapter 2, Verse 12

It is not that I have never existed, nor you, nor these kings. Nor is it that we shall cease to exist in the future.

There was never a time you didn't exist. There never will be a time you stop.

Before anything else, Krishna wants Arjuna to know what he actually is: not this body, but something that doesn't end when the body does.