《资治通鉴·隋纪·隋纪四》
长孙晟说： 天子巡幸所到之地，诸侯都要亲自洒扫，修整御道，以表示对天子的至诚崇敬之心。现在牙帐内杂草丛生，我只说是留着香草罢了！ 
晟曰： 天子行幸所在，诸侯躬自洒扫，耕除御路，以表至敬之心；今牙内芜秽，谓是留香草耳！ 
Changsun Sheng said, "In places where the emperor has inspected, the vassals have to clean the ground and renovate the imperial road to show their utmost respect to the emperor. Now there is such a mess in your tent, and I only say that I will clean the fragrant grass!"