The Art of War by active 6th century B.C. Sunzi

3. After crossing a river, you should get far away from it.

["In order to tempt the enemy to cross after you," according to Ts’ao Kung, and also, says Chang Yu, "in order not to be impeded in your evolutions." The _T’ung Tien_ reads, "If _the enemy_ crosses a river," etc. But in view of the next sentence, this is almost certainly an interpolation.]