《后汉书·列传·南蛮西南夷列传》
张乔于是派从事杨竦率领人马到棵榆进攻贼寇，但贼寇强盛，杨竦没敢前进，先将韶书传告三郡，秘密征求武士，悬重赏。
乔乃遣从事杨竦将兵至榆击之，贼盛未敢进，先以诏书告示三郡，密征求武士，重其购赏。
Zhang Qiao therefore sent the administrator Yang Song to lead troops to Ke Yu to attack the rebels. However, the rebels were powerful and Yang Song dared not advance. He first distributed the decree to the three prefectures, secretly recruiting soldiers and offering large rewards.