《北史·列传·卷二十二》
昭王对他说： 您为书籍注疏，以烛光继续白天的工作，白天还可以，晚上应当休息。 
昭王曰： 卿注记篇籍，以烛继昼，白日且然，夜可休息。 
Emperor Zhao said to him: You annotate books, continue your work during the day with candlelight, it is okay during the day, but you should rest at night.