Chapter 2, Verse 4 - Sun Tzu

Now, when your weapons are dulled, your ardor damped, your strength exhausted and your treasure spent, other chieftains will spring up to take advantage of your extremity. Then no man, however wise, will be able to avert the consequences that must ensue.
~ from The Art of War, Giles translation ~

Go here to read the introductory post to the verses of The Art of War.