Chapter 13, Verse 26 - Sun Tzu

Of old, the rise of the Yin dynasty was due to I Chih who had served under the Hsia. Likewise, the rise of the Chou dynasty was due to Lu Ya who had served under the Yin.
~ from The Art of War, Giles translation ~

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