《新唐书·列传·卷三十七》
柳泽进宫呈递奏疏说： 我听说药剂不毒就不能消除疾病，话不急切就不能补救过失。
泽诣阙上疏曰：臣闻药不毒不可以蠲疾，词不切不可以补过。
Liu Ze entered the palace and presented a memorial, saying: I have heard that medicine cannot cure illness if it is not toxic, and words cannot correct mistakes if they are not urgent.