《资治通鉴·唐纪·唐纪六十二》
朝廷鉴于回鹘屯居天德、振武北边边境，任命兵部郎中李拭为巡边使，让他考察将帅的军事才能。
朝廷以回鹘屯天德、振武北境，以兵部郎中李拭为巡边使，察将帅能否。
Given that the Uighur camped at the northern border of Tiande and Zhenwu, the imperial court appointed Li Shi, the assistant official of the Ministry of War, as a border patrol envoy to assess the military capabilities of the generals.