Chapter 6, Verses 22 and 23 - Sun Tzu

Though the enemy be stronger in numbers, we may prevent him from fighting. Scheme so as to discover his plans and the likelihood of their success. Rouse him, and learn the principle of his activity or inactivity. Force him to reveal himself, so as to find out his vulnerable spots.
~ from The Art of War, Giles translation ~

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