唐憲宗元和四、五年間，李益回洛陽老家向父母祝壽。離別時，當時洛陽士大夫皆有拜送，韓愈送之以序，藉著他與幽州劉濟的舊情，期望李益回朝後，後韓愈與宰相李藩的對話轉告，期盼劉濟效忠王室，率藩將入覲述職。而李益大抵曾傳韓愈此語於劉濟，時間不晚於元和五年七月劉濟死前。筆者對於本文的「繫年」、「幽州端公」、「使歸」與傳語等幾個問題，經過考辨，認為以繫元和四年二月至五年三月前為宜；《舊注》以為當時李益在幽州幕，實誤；李益其後大抵以書函以語與劉濟，並無出使之事。

Li I returned to his hometown at Lo-Yang to celebrate the birthday of his parents during the fourth or fifth year of Y?an Ho Reign of the Tang Dynasty. For the occasion, many of high officers sent him farewell gifts. Han Y? sent him a farewell essay in which Han asked him to transmit to Liu chi the message expanded between Prime Minister Li Fan and himself. In order to persuade Liu Chi to resume his loyalty to the Emperor due to the nice connection between Li I and Liu chi. Li I did transmit this message to Liu Chi no later than Liu’s death at the July of the fifty year of the Y?an Ho Reign. With respect to the chronological problem of Han’s essay, whether or not Li I worked as officer at Yu Chou, and whether or not Li I was on mission as a messenger, in view of all evidences, I conclude that Han’s essay should be dated between February of the fourth year of the Y?an Ho Reign and March of the fifth year of the Y?an Ho Reign. The traditional view that Li I worked at that time at Yu Chou is wrong. Li I did transmit the message to Liu Chi but by letter, without taking the mission as a messenger.