《左传·哀公·哀公二十年》
于是就前去，先到越军那里，说： 吴国冒犯上国已经多次了，听说君王亲自讨伐，中原的人们莫不欢欣鼓舞，惟恐君王的意愿不能实现，请让我进去看看吴军的情况。 
乃往。先造于越军，曰： 吴犯间上国多矣，闻君亲讨焉，诸夏之人莫不欣喜，唯恐君志之不从。请入视之。 
So they went, first to the Yue army, saying: "Wu has offended the Zhongyuan state many times, and I have heard that the king has personally led an expedition, and the people of Zhongyuan are very happy, only fearing that the king's will cannot be fulfilled, so I ask to go in and see the situation of the Wu army."