In the early years of the Tang Dynasty, Emperor Taizong of Tang Li Shimin rewarded founding father Wei Zheng and wanted to give him several beautiful women as concubines. Wei Zheng refused in every possible way, but Li Shimin still insisted that Wei Zheng take concubines. The matter spread to the ears of Mrs. Wei, who was fierce by nature, and stormed the Golden Palace in anger to argue with Li Shimin. Li Shimin was displeased: "Why did the fifth sister-in-law break into the Golden Palace?" Mrs. Wei said angrily, "Why did Your Majesty break up our loving husband and wife?"

Li Shimin asked, "What do you mean by that?" Madam Wei said, "Why does Your Majesty insist that Wei Zheng take a concubine?"

Li Shimin said: "I just gave him a few beautiful women as concubines, and the fifth sister-in-law is still the main house, why break up?"

Madam Wei became even more angry when she heard this and said, "Which man does not have a new love and then abandon the married couple? Your Majesty insists that Wei Zheng take a concubine, I might as well die!"

Li Shimin's long face was furious and said, "I will fulfill you." Then he ordered someone to bring poisoned wine. In fact, Li Shimin just wanted to make a joke, and ordered someone to take poisoned wine instead of poisoned wine, but Cheng Yaojin, who didn't know the inside story, saw that the situation was not good and went out to replace the fake poisoned wine with vinegar.

When the "poisoned wine" was delivered, Mrs. Wei was not afraid and drank all the vinegar in the pot in one go. Who knew that after half a day, toxicity did not occur, and only felt sour in his mouth. At this time, Cheng Yaojin joked: "Fifth sister-in-law, how does the poisoned wine taste?" Mrs. Wei glared at him, "Bah, it's almost like vinegar." Cheng Yaojin laughed "haha": "Fifth sister-in-law can be jealous so much, what a vinegar vat."

This is the origin of jealousy.