Bhagavad Gita, Chapter 2, Verse 36

Your enemies too, mocking your strength, will say things about you that should not be said. And what, indeed, could be more painful than that?

Your enemies wouldn't just win. They'd get to mock you for it, permanently.

Krishna points out a harder truth: stepping back doesn't just cost the battle, it hands your rivals a story to tell about you. That kind of humiliation cuts deeper than losing.