前倨后恭

be haughty at first but respectful later

This idiom comes from Intrigues of the Warring States·Intrigues of Qin I. During the Spring and Autumn Period and the Warring States Period,there was afamous Political Strategist named Su Qin. He and Zhang Yi had learned the political strategy from Guiguzi.

Before Su Qin's success, he went out preaching, accomplishing nothing at all. So every time he returned home, he was treated coldly by his family and county people.They all considered him goodfor nothing. Especially his sister-in-law pointed out that he idled about and did no decent work every day, and also said he could never hold up his head in future.

Since then Su Qin studied very hard from morning till night. Even tieing his hair to a beam to keep from nodding, or proding himself awake with an awl in the thigh, he studied assiduously. Finally he achieved great success in bringing the six states together to resist the strong State of Qin.

He was offered prime minister by Duke Wen of Yan and also to be Marquis Wuan by Duke of Zhao. Once on his way to the State of Chu, when he passed through his native town--Luoyang, his parents welcomed him at the countryside and his sister-in-law got down on her knees and asked for forgiveness. Then Su asked:"Why are you so arrogant before but respectful now." She was ashamed and said : "Because now you are not only in high post but also rich." Hearing this, Su left a deep sigh and said: "Why do all the common people treat others only by their position and wealth?"

Now we use it to describe that some snobs adopt different manners towards the other's failure or success.

此语出自《战国策·秦策一》。春秋战国时代，有位著名的纵横家叫苏秦。他曾和张仪一起拜鬼谷子为师，学习“纵横之术”。

当苏秦尚未成名之时，他外出游说，一事无成。每次他穷困潦倒地回到家中，都受到众人的冷落，被认为没有出息。特别是他的嫂子骂他游手好闲，不务正业，断言他永无出头之日。

为此苏秦发愤读书，甚至“悬梁刺股”地刻苦读书。学成后他又外出游说，终于游说六国成功，一起对付强大的秦国。

他被燕文公拜为相国，又被赵肃侯封为武安君，挂相印。他在去楚国的路上，路过洛阳，他父母特地到洛阳郊外迎接他，他的嫂子却伏地长跪不起向他请罪。苏秦见了问她：“嫂嫂，你为什么从前那么傲慢，而今天却这样卑恭呢?”他嫂子又愧又怕地说：“那是因为小叔现在职位高，金钱多啊！”苏秦听了，长叹一声地说：“人世间，不以贫贱富贵来待人的人实在太少了！”

后用此典讽刺那些势利小人先是傲慢待人，见人成功后又恭敬，前后态度不一样。