Martial Arts Proverbs - The Tiger

人無傷虎心虎有傷人意

"Even if a man has no desire to harm a tiger, the tiger certainly intends to harm the man."

This refers to defending yourself against an opponent. It's important to remember that even if you didn't want to fight to begin with, you're being attacked, and must consider your attacker to be like a ferocious tiger. In other words you can't defend yourself half-heartedly.