《资治通鉴·唐纪·唐纪二十八》
戊戌，唐玄宗发布敕命： 五品以上的京官，各州刺史及京兆、河南、河中、太原四府的府尹、少尹，每人向朝廷推荐一位县令，朝廷将根据其政绩的好坏对举荐者进行赏罚。 
戊戌，敕： 京官五品以上，外官剌史、四府上佐，各举县令一人，视其政善恶，为举者赏罚。 
On Wuwu, Tang Xuanzong issued an edict: Metropolitan officials above the fifth rank, governors of various states, and the governors and vice-governors of the four prefectures of Jingzhao, Henan, Hezhong, and Taiyuan, each recommend a county magistrate to the imperial court, and the imperial court will reward or punish the recommender based on the official's performance.