During the Tang Dynasty, there was a notorious villain named Li Linfu who, though utterly unlearned, was a master of flattery. The aging and befuddled Emperor Xuanzong, mistaking his sycophancy for loyalty, promoted him to prime minister.
Li Linfu, who held immense power, relentlessly targeted anyone who opposed him to secure his influence. At the time, Yan Tingzhi, a Vice Director of the Secretariat, openly disapproved of Li Linfu's actions. In response, Li Linfu slandered Yan Tingzhi before Emperor Xuanzong, spreading false rumors that led to Yan's demotion to serve as a prefect in remote regions like Luozhou and Jiangzhou.
Some time later, Emperor Xuanzong remembered Yan Tingzhi, thinking highly of him and wanting to reappoint him, so he ordered Li Linfu to summon him.
After the court session, Li Linfu found Yan Tingzhi's younger brother Yan Sunzhi and said to him, "The emperor still cares about your brother and wants to see him. Could you ask your brother to write to the emperor, saying he has rheumatism and requests to come to the capital for treatment?"
After Yan Sunzhi conveyed Li Linfu's intentions to his brother, Yan Tingzhi, unaware of the scheme, actually submitted a memorial to the emperor. Li Linfu seized the opportunity to tell Emperor Xuanzong, "Yan Tingzhi is old and suffering from rheumatism; he likely cannot hold an important post. Your Majesty should assign him a sinecure so he can focus on recuperating."
When Emperor Xuanzong heard Li Linfu’s words, he had no choice but to abandon the idea of promoting Yan Tingzhi.
Left Chancellor Li Shizhi was straightforward and outspoken, which made Li Linfu resent him. One day, Li Linfu said to Li Shizhi, "There is a gold mine near Mount Hua. If we could mine it, the nation would become wealthy."
Li Shizhi believed his words and reported this to Emperor Xuanzong at court. The emperor, having never heard of it, asked Li Linfu. Li Linfu replied, "I have long known, but because Mount Hua is the foundation of the imperial house and the seat of royal aura, it is unsuitable for mining, so I did not mention it."
After hearing this, Emperor Xuanzong felt that Li Linfu always had the empire's foundation in mind and was very pleased. He then reprimanded Li Shizhi, saying, "From now on, when anything comes up, consult with Linfu first before reporting to me—don't be so rash."
From that point on, Li Shizhi steadily lost favor in Emperor Xuanzong's eyes.
In 747 AD, Emperor Xuanzong of the Tang Dynasty issued an imperial decree summoning all talented individuals across the empire to the capital Chang'an for an examination. Fearing these candidates might expose his misdeeds before the throne, the chancellor Li Linfu proposed that the Department of State Affairs conduct the exams instead. As a result, not a single person was selected. Thus, Li Linfu dashed the promising futures of countless gifted scholars. He then congratulated the emperor, saying, "That no one passed is excellent news—it proves there are no hidden talents left in the realm."
At that time, people said Li Linfu had "honey in his mouth and a sword in his belly," hating him to the bone. Later, people used the idiom "honey-mouthed, sword-bellied" to describe someone sweet-talking but venomous, extremely cunning and treacherous.
Source: *Zizhi Tongjian*, Chapter "Emperor Xuanzong of Tang, Tianbao First Year"
Meaning of the Idiom: Later, the Chinese idiom "口蜜腹剑" came to describe how someone sweet-talking but venomous, extremely cunning and treacherous.