《旧唐书·列传·卷十五》
太宗又命令驾车准备去吊唁，司空房玄龄认为太宗刚刚服药，不能吊丧，上表极力劝谏，太宗说 ：我这次去，哪里只是为尽君臣的礼节，还因为老友的情感深厚，亲戚的关系重大，您别再说了。 
太宗又命驾将临之，司空玄龄以上饵药石，不宜临丧，抗表切谏，上曰： 朕之此行，岂独为君臣之礼，兼以故旧情深，姻戚义重，卿勿复言也。 
Taizong ordered a carriage to prepare for the memorial service. Sikong Fang Xuanling believed that Taizong had just taken medicine and could not mourn. He strongly advised him to say: This time I went, where is not only to fulfill the etiquette of the monarch and minister, but also because of the deep love of old friends and the importance of kinship. You don't have to say any more.