三十六计 Thirty-Six Stratagems: 笑里藏刀 Hide a knife behind a smile
Chapter 2: Enemy Dealing Stratagems 敌战计
Li Yufu (李义府 Lǐ Yìfǔ) was a scheming (狡诈的 jiǎozhàde) Tang minister who had a way with people. He seemed kind and friendly, but woe betide anyone who crossed him. He cultivated good terms with the Emperor who ignored complaints about him for a long time, but eventually banished him to a frontier post. Many years later, a poet wrote of Li Yufu, where 'a dagger hides behind the smiles'.
A critical principle of this stratagem is delay (拖延 tuōyán). Armies are often eager for battle, but waiting for the best moment can not only increase the chance of success, but also being able to do so with minimum loss.