In the Spring and Autumn Period, Chong Er, the son of a feudalprince in the State of Jin fled from Jin in order to avoid being killed. He came to State of Chu, persevering through hell and high water.
King Chu treated him very well. One day, he invited Chong Er for dinner. They chatted while drinking. Suddenly King Chu asked Chong Er, "If one day, you become a king, how will you thank me?" Chong Er replied, "jewelry and beauties, you have plenty of. What else can I send?"
King Chu said, "So it has been said, but you have to express your thanks, don't you?" Chong Er smiled, "If I were to become the king later, in the event that war occurred between our countries, I would order my army to retreat 60 miles".
四年后,重耳真的当了国君。公元前633年,楚国跟晋国在战争中相遇,重耳也依照约定,往后退了三舍。
Four years later, Chong Er did indeed become a king. In 633 BC, the State of Chu and Jin encountered each other in war and Chong Er kept his promise to order his army to retreat.