《容斋随笔·卷十二·虎夔藩》
杜甫《课伐木》诗的诗序说： 督促罪犯到山谷中砍伐山阴的树木，早上出去，晚上回来，我们有篱笆，那儿缺了就在哪儿补上，居处的地方于是能够稍得安宁。
惟杜工部《课伐木》诗序云： 课隶人入谷斩阴木，晨征暮返，我有藩篱，是阙是补，旅次于小安。
Du Fu's poem "Lesson on Logging" says in the preface: Urge criminals to go to the valleys to cut down trees on Shanyin, go out in the morning and return at night, we have fences, fill in the gaps wherever they are, and the place where we live can thus be slightly more peaceful.