《新唐书·列传·卷五十六》
见到皇帝后，以素衣待罪，皇帝不加罪，待遇与过去一样。李勉自觉惭愧，内心不安。以后，只照常规办事，不敢再有所建议。
既见帝，素服待罪，诏不许，勉内愧，取充位而已，不敢有所与。
After seeing the emperor, he waited for guilt in plain clothes, the emperor did not punish him, and the treatment was the same as before. Li Mian felt ashamed and uneasy. Later, he only acted according to the routine, but did not dare to make any more suggestions.