There are poems coming and going, making a big axe in front of Lu Ban.
This is a poem named Li Bais Tomb written by Mei Zhihuan in Ming Dynasty. Li Bai, whose word is too white, likes drinking, and is called Li Chenxian, a great poet in the Tang Dynasty. There are all kinds of myths and legends about his death. For example, some people say that Li Bai visited Dongting, Yueyang and Jinling (now Nanjing) in his later years. One day, boating quarried by the river (quarrying, in today's dangtu county, Anhui Province, bordering the Yangtze River in the north). At night, the moon was bright as day, and Li Bai was drunk on the boat. When he saw the shadow of the moon in the water, he bent down to catch it and fell into the river. Some legends are even more magical. It is said that at this moment, there was a sudden storm on the river, and a giant whale and two fairies appeared, tinkling in their hands, asking Li Bai to sit on the whale's back, led by music, and flew away. Of course, these legends can't be believed, but in quarrying, many places of interest appeared later. There are not only Li Bais Tomb, but also the Fairy Tower and the Moon-catching Pavilion, which have aroused the interest of countless tourists. It's ridiculous that some tourists who want to pretend to be elegant even make up questions in Li Bais Tomb. This poem by Mei Zhihuan is a mockery of such tourists. He thinks that scribbling crooked poems on the grave of a great poet is simply "making a big axe in front of Lu Ban"-too careless.
It is said that Lu Ban, who has lost his surname, was a native of Lu during the Warring States period, also known as Lu. He is an expert in making precision instruments, and people call him an "able man". People always think that he is the ancestor of carpenters. Who dares to show off his axe skills in front of Lu Ban? In other words, trying to show your skills in front of experts is a ridiculous act of being too modest, which is called "playing axe in front of Lu Ban" or "playing axe in front of the door". It is similar to the saying that "playing a big knife in front of Guan Gong".
Liu Zongyuan, a writer in the Tang Dynasty, said in the preface to "Singing a Peace Poem for the Match of the King": "When you get to the door of the class, you will be strong." (it should refer to another ancient axe hand. See "Axis Correction". "Strong face" means having a thick face. It seems that the idiom "teach others to teach axes" was not only born out of the above poem of Mei Zhihuan in the Ming Dynasty, but its embryonic form existed as early as the Tang Dynasty.
This idiom is sometimes used as a self-deprecating word to show that you dare not show your skills in front of experts.