Learn archery from Yi and teach archery as much as possible. Thinking that only Yi could surpass himself in archery, he killed Yi. Mencius said, "It is easy to make mistakes." The monarch said to Yi, "It can be said that B is innocent."

Mencius said, "Since his friendship is as thin as a cloud, how can he be said to be innocent? For example, the people of Zheng let Zhuo Zi's son invade Wei, and Wei sent foolish men to hunt him down. Zizhuo's son said, "I'm sick today, so I can't shoot an arrow with a bow." ... (probably because my son and Yu Fen are apprentices, and my son doesn't want to take a taxi).