wikipedia fact
Doulu's and Wei's downfall, however, would come shortly after that. Doulu, after completing Li Cunxu's tomb, returned to his mansion and waited for the next assignment, as was traditional at the time for a director of an imperial tomb, and he expected to be removed from his chancellor position but made a circuit military governor. After several days, however, the next imperial commission did not come, and at the urging of his family members and friends, he went to the imperial court, implicitly pressing the issue. This offended An, who publicly humiliated Doulu by stating, "Your title of director of the imperial tomb is still present, but you do not wait for the new assignment before coming to the imperial court. Is it that you believe that we, as people from a border region, can easily be deceived?" (Both Li Siyuan and An were non-Han Chinese.) Doulu and Wei were also being perceived poorly publicly for several different reasons — they were considered to be disrespectful to the emperor while reporting to him; while other imperial officials at that time were taking a reduced amount of their salaries, Doulu and his sons were receiving full pay; and while the other imperial officials backpay were being calculated from the day of Li Siyuan's ascension, Doulu and Wei were still calculating their own from during the time of Li Cunxu's reign. Meanwhile, Xiao Xifu had long resented Doulu and Wei for having rejected his earlier proposed promotion to Jianyi Daifu (諫議大夫), and therefore decided to take vengeance. He submitted a petition in which he not only accused Doulu and Wei of flattery and faithlessness to Li Cunxu, but further falsely accused Doulu of seizing people's farms and allowing his farmer tenants to kill others, and Wei of seizing a neighbor's well in order to steal the treasures that the neighbor's ancestors had hidden in the well. Upon receiving Xiao's petition, Li Siyuan exiled Doulu and Wei — in Doulu's case, to be the prefect of Chen Prefecture (辰州, in modern Huaihua, Hunan), then as census officer of Fei Prefecture (費州, in modern Tongren, Guizhou), and then completely stripped of official positions and exiled to Ling Prefecture (陵州, in modern Meishan, Sichuan).