《新唐书·列传·卷八十二》
现在，朔方、太原的部队已驻扎在华山以东，而神策军的六支部队全部镇守在函谷关外，将领不能抵挡敌军，就请求增兵，陛下为此撤掉边防部队，抽空禁卫军。
今朔方、太原众已屯山东，而神策六军悉戍关外，将不能尽敌，则请济师。
At present, the troops from Shuofang and Taiyuan have stationed east of Huashan, and the six armies of Shence have been guarding outside Hangu Pass, and if the generals cannot resist the enemy, they request for reinforcements, and thus His Majesty withdraws the border troops and weakens the imperial guards.