Because friends will have a great influence on yourself. Friends who are straight, friends who are understanding, and friends who are knowledgeable are beneficial. "Friends will help you, friendliness will help you, and friends will help you to be harmed." That is: There are three kinds of friends who benefit people, and there are three kinds of friends who hurt people: honest friends, sincere and trustworthy friends, knowledgeable and knowledgeable friends Friends who are knowledgeable can benefit us a lot; but in fact, friends who are not upright, who are good at catering to others, and who lack integrity, who are good at talking nonsense but have no real talent and knowledge, will only make us suffer.