How did the most confusing phrase "Speak of the devil" in the Three Kingdoms come into being?

A few years ago, there was a riddle asking who ran fastest during the Three Kingdoms period. The answer is not Guan Yu riding a red hare, nor Liu Bei who is often driven away, but Cao Cao. The reason is that there is a saying "Speak of the devil". The meaning of this proverb is already very confusing. What is the original intention and origin?

Allusion: After Dong Zhuo was killed, Li Jue followed Jia Xu's plan, occupied Chang 'an and took control of state affairs. Soon, Li Jue and Guo Si got into a fight, and Emperor Xiandi escaped from danger. Later, under the mediation of Zhang Ji, Li Jue and Guo Si merged and regained the son of heaven. At this time, Cao Cao was recommended to save the driver. Emperor Xian of Han was in a hurry to go to the hospital, and quickly sent messengers to Cao Cao for help. But the emissary was surrounded by Li Guo's allied forces before he set out. At this critical moment, he was suddenly killed, claiming that Cao Cao ordered his army to "escort" and defeated Li and Guo. Therefore, there is a saying called "Speak of the devil and he will arrive".

This is a folklore. The emissary of Emperor Xian of Han Dynasty did not set out from here, but Cao Cao took the initiative to send someone to rescue him. The novel Romance of the Three Kingdoms is different. After receiving the imperial edict from Emperor Xian of Han Dynasty, Cao Cao sent troops from Shandong to Luoyang, where he defeated Li Jue and Guo Si. In fact, Emperor Xian of the Han Dynasty sent rescue letters to Yuan Shao and Cao Cao respectively, but Yuan Shao ignored Emperor Xian of the Han Dynasty as a burden. Cao Cao, on the other hand, seized the opportunity and took the lead everywhere. Either way, it is similar, and the person who describes what he thinks unexpectedly appears in front of him, giving people a surprise.

Later, with the plastic surgery of Cao Cao's treacherous court official image, it gradually derived another meaning. It is a powerful minister like Cao Cao who planted eyes and ears everywhere in order to control public opinion and monitor officials. So be careful what you say and do, and don't let Cao Cao's eyes and ears catch you. Later, this proverb became a riddle and was completely broken.