《新唐书·列传·卷六十九》
现要他回去，必定不能建功，这是白派他回去了；如果他立了功，按道理不能夺他的权，那么因为蜀地闭塞，战败了当然就丢了，战胜了也不归朝廷拥有。
则西蜀之奥，败固失之，胜亦非国家所有。
Now if he were to be ordered to return, he would definitely not be able to achieve anything, and sending him back would be in vain; if he were to achieve something, then according to reason his authority could not be seized, and so because the terrain of Shu is closed off, if he were to lose a battle he would of course lose his authority, and if he were to win the battle the rewards would not return to the court.