《旧唐书·列传·卷一百四十》
等到百官列于朝廷，才发现有缺于礼节，宰相相顾失色。
及百僚在列，方知阙礼，宰相相顾失色。
When all the officials were lined up in the court, they realized that there was a lack of etiquette. The prime minister and the other ministers looked at each other in dismay.