口蜜腹剑 — “To have honey in one's mouth and a dagger in one's heart”

The idiom "口蜜腹剑" (kǒu mì fù jiàn), which literally means "honey in mouth, sword in belly," describes someone who speaks sweetly and kindly on the surface but harbors malicious intentions and schemes to harm others in their heart. It characterizes a hypocritical and treacherous person.

This idiom originates from *Zizhi Tongjian (Comprehensive Mirror in Aid of Governance)*, specifically "Annals of Tang, Emperor Xuanzong, Tianbao First Year." It refers to Li Linfu, a prominent chancellor during the reign of Emperor Xuanzong of the Tang Dynasty.

Li Linfu, serving as the Minister of War and concurrently Chancellor, was known for his administrative skills and talent in calligraphy and painting. However, his character was deeply flawed. He was extremely jealous of capable and respected scholars, often resorting to unscrupulous means to suppress and harm those whose talents, reputation, or influence rivaled his own. To maintain his position and power, he was adept at flattery, constantly appeasing Emperor Xuanzong and currying favor with the emperor's beloved concubines and trusted eunuchs. Outwardly, Li Linfu always appeared warm and amiable, speaking with pleasant and seemingly well-intentioned words. Yet, beneath this facade, he was cunning and treacherous, constantly plotting against others in secret.

A notable incident illustrates his duplicity. Once, he feigned sincerity and suggested to his colleague Li Shizhi that Mount Hua was rich in gold, and its mining could greatly enrich the nation, adding that the Emperor was unaware of this potential. Believing Li Linfu, Li Shizhi eagerly proposed the mining project to Emperor Xuanzong. The Emperor was delighted and immediately summoned Li Linfu for consultation. To Li Shizhi's surprise, Li Linfu then contradicted himself, stating, "I have long known about this, but Mount Hua is a sacred place, a 'feng shui' hub for emperors. How can one casually mine it? Those who advise you to do so might have ulterior motives. I've often wanted to mention this to you, Your Majesty, but dared not." Emperor Xuanzong was deeply moved by Li Linfu's words, believing him to be a loyal and patriotic minister. Consequently, Xuanzong became displeased with Li Shizhi and gradually distanced himself from him.

Through such cunning tactics, Li Linfu managed to hold the position of prime minister for nineteen years. Later, Sima Guang, when compiling *Zizhi Tongjian*, aptly described Li Linfu as a person who had "honey in his mouth and a sword in his belly," a description that perfectly captured his insidious nature.