《国语·晋语·栾书发郤至之罪》
发钩就这样对晋厉公说了，厉公告诉了栾书，栾书回答说： 我早已听说了，郤至准备作乱，叫苦成叔故意延缓齐、鲁两国出兵，自己却劝君王作战，一旦晋军战败，就迎接孙周回国为君，后来事情没有成功，因此故意放楚王逃走。
发钩告君，君告栾书，栾书曰： 臣固闻之，郤至欲为难，使苦成叔缓齐、鲁之师，己劝君战，战败，将纳孙周，事不成，故免楚王。
Fahou thus spoke to Duke Li of Jin. The duke told Luan Shu, who replied, "I have long heard that Xi Zhi was planning to rebel, and told Ku Chengshu to intentionally delay the troops of Qi and Lu, while he himself persuaded the king to go to war. Once the Jin army was defeated, he would welcome Duke Sun Zhou back to the country to become king. Later, the plan did not succeed, so he intentionally let the King of Chu escape."