《宋史·列传·卷一百二十五》
先写信送给吴，说杀金平地势开阔，前面的防线分散漫长，必须在后面险隘地区建立第二道防线，然后才能够战胜敌人。
先以书抵玠，谓杀金平地阔远，前阵散漫，须后阵阻隘，然后可以必胜。
First write a letter to Wu, saying that the terrain of Shajiping is open and the front line is scattered and long. It is necessary to establish a second line of defense in the dangerous area in the back before we can defeat the enemy.