《左传·昭公·昭公十年》
齐景公为了派王黑用龙旗领兵而占卜，吉利，请求砍去三尺以后再使用。
公卜使王黑以灵姑率，吉。请断三尺焉而用之。
Duke Jing of Qi divined the auspiciousness of sending Heikei to lead troops with the dragon flag, and requested it be cut by three feet before using it.