《史记·三十世家·郑世家》
郑人担心这件事，就派人私下对秦国说： 打败了郑国对晋国有好处，并非对秦国有利。 
郑人患之，乃使人私於秦曰： 破郑益晋，非秦之利也。 
The people of Zheng were worried about this matter so they sent someone to privately tell Qin: Defeating Zheng will bring benefits to Jin, but not to Qin.