Enter My Room And Take My Spear Against Me--Ru Shi Cao Ge

This Chinese of Enter My Room And Take My Spear Against Me--Ru Shi Cao Ge is 入室操戈, and Pin Yin rù shì cāo gē .
During Eastern Han Dynasty of China, there lived a famous scholar and educationists named Zheng Xuan.
When he was young, Zheng Xuan studied very hard, which helped him win the favor of the governor Du Mi who thought of him as a rough diamond. With Di Mi's recommendation, Zheng Xuan was allowed to study in the government school, where he enriched his knowledge and became a scholar of some note.

Later, he took Ma Rong, a influential Confucian scholar of Eastern Han Dynasty, as his teacher. When he finished his study, leaving, Ma Rong said:" Zheng Xuan is leaving, and all my knowledges are going with him. "
After coming back home, Zheng Xun continued to apply his mind to his studies. Once, He Xiu, one of his good friends, wrote three articles and sent to him for comments. Disagreeing with He Xiu's opinions, Zheng Xun also wrote three articles to refute He Xiu's arguments one by one. His articles were very convincing and persuasive, because he cleverly used He Xiu's own points to retort upon He Xiu.
Having Read Zheng Xuan's articles, He Xiu admired his knowledge and writing skilled very much, saying to him: " My friend, is it that you enter my room and take my spear against me? "

Background and Writer Comment:

This Chines idiom story is from "The History of the Later Han (后汉书)", one of the official Chinese historical works which covers the history of Eastern Han from 25 to 220.
The idiom of Enter My Room And Take My Spear Against Me--Ru Shi Cao Ge refers to using one's own points to retort upon him.
This idiom looks quite similar with another Chinese idiom "Tong Shi Cao Ge--Family Members thrust At Each Other With Spears", but has a very different meaning.