《旧唐书·本纪·卷十八》
牛僧孺说 ：现在百官分析情况，认为固守关隘防地，等待可以进击敌军的时候再用兵为妥。 
僧孺曰： 今百僚议状，以固守关防，伺其可击则用兵。 
Niu Sengru said: Now all the officials analyze the situation and believe that it is better to stick to the passes and defend the stronghold and wait until the time to attack the enemy.