Chapter 9, Verses 15 and 16 - Sun Tzu

Country in which there are precipitous cliffs with torrents running between, deep natural hollows, confined places, tangled thickets, quagmires and crevasses, should be left with all possible speed and not approached. While we keep away from such places, we should get the enemy to approach them; while we face them, we should let the enemy have them on his rear.
~ from The Art of War, Giles translation ~

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