《左传·昭公·昭公十三年》
等到结盟的时候，子产争论进贡物品的轻重次序，说： 从前天子确定进贡物品的次序，轻重是根据地位排列的。地位尊贵，贡赋就重，这是周朝的制度，地位低下而贡赋重的，这是距天子附近的小国。
及盟，子产争承曰： 昔天子班贡，轻重以列，列尊贡重，周之制也，卑而贡重者，甸服也。
When the alliance was forged, Zichan argued about the sequence of tribute offerings, saying: The Emperor of the past established that the sequence of tribute offerings was arranged according to rank. If the rank was noble, the tribute was heavy. This was the institution of the Zhou Dynasty. If the rank was low but the tribute was heavy, this was the small state that was close to the Emperor.