This is a story from Three Kingdoms.

Zhou Yu of Wu Kingdom was a strategist but he was narrow-minded and jealous of people smarter than him. So he had always been thinking of killing Zhuge Liang and Liu Bei of Shu Kingdom.

One day, he invited Liu Bei to cross the river, while did not let Zhuge Liang-who was then staying in Wu for help-know about it. Zhou Yu was very glad when he saw Liu Bei's coming. He had arranged an armed man to kill Liu Bei at the banquet（宴会，盛宴） when he threw a cup to the ground as the signal.

Zhuge Liang was surprised when he discovered Liu Bei were meeting with Zhou Yu. Anxiously he went to the tent and relieved to see Liu Bei had Guan Yu standing behind to protect him. Then he went to a small boat by the river, waiting for them to come back.

At the banquet, host and guest had savored（尽情享用） several rounds of wine when Zhou Yu stood up, cup in hand. Observing Lord Guan, hand on sword, Zhou Yu inquired who he was, "My younger brother, Guan Yunchang," replied Liu Bei. "Not the one who cut down generals Yan Liang and Wen Chou?" Zhou Yu asked nervously. "The same," Liu Bei answered. Zhou Yu, alarmed, broke out in a cold sweat. He poured a cup for Lord Guan and drank with him and said, "You are really famous for you have slain six generals and breached five passes!"

When Liu Bei asked where Zhuge Liang was, Zhou Yu said he'd better meet him when Cao Cao was defeated. Lord Guan eyed Liu Bei, who sensed his brother's intent and rose to bid Zhou Yu farewell. Zhou Yu made no effort to detain his guests.

When Liu Bei and Lord Guan reached the edge of the river, where they were happy to find Zhuge Liang in his boat. "My lord," said Zhuge Liang , "You were in more danger than you knew today. If not for Lord Guan, Zhou Yu would have killed you."