《汉书·传·窦田灌韩传》
我听说利益达不到十倍时，绝不改变原来的职业，功利达不到百倍时绝不更改固定的事业，因此古代的人君谋划事情时必以祖宗成法为例，施政也要查问典，这是因为做事难的缘故。
臣闻利不十者不易业，功不百者不变常，是以古之人君谋事必就祖，发政占古语，重作事也。
I heard that when the benefits are less than ten times, never change the original profession, and when the benefits are less than a hundred times, never change the fixed career. Therefore, when the ancient monarchs planned things, they must use the ancestral laws as an example, and when they govern, they must also Consult the classics, this is because it is difficult to do things.