《新唐书·列传·卷七十九》
两家早晨若没有钟鼓声，执金吾就会报告给皇帝，稍后，朝廷使者来了，必定说： 今天为什么不奏乐？ 
两家日出无钟鼓声，则金吾以闻，少选，使者至，必曰： 今日何不举乐？ 
If the two families did not hear the sound of bells and drums in the morning, the commander of the imperial guards would report it to the emperor. Later, the imperial envoy would come and say, "Why didn't you play music today?"