《新唐书·列传·卷四十三》
张廷珪陈述五条不可行的理由，还说： 中国步兵多骑兵少。每个士兵带一石粮食，背百斤重的盔甲，盛夏时长途跋涉，昼夜不得休息，与回纥相比，劳逸悬殊，其势自然不能相抵，此其一。
王琚持节巡天兵诸军，方还，复诏行塞下，议者皆谓将袭回纥，廷珪陈五不可，且言： 中国步多骑少，人赍一石粮，负甲百斤，盛夏长驱，昼夜不休，劳逸相绝，其势不敌，一也。
Zhang Tinggui stated five infeasible reasons, also saying: China had more infantry than cavalry. Each soldier carried a stone of grain and heavy armour weighing a hundred pounds, and they travelled long distances in the heat of summer without rest, day or night. Compared to the Uighurs, their exertions did not balance their ease, and they were naturally no match for them; this was the first point.