Give the wrong-doer a way out
Beginning with Yu the GREat, the Xia Dynasty had lasted about four hundred years before Jie became the supreme ruler.
And that was in the 18th century BC. Jie was extremely tyrannical and dissolute. This aroused GREat resentment among the people. Tang, the Chief of the tribe Shang took advantage of this situation to overthrow the Xia Dynasty and established the Shang Dynasty in the early 17th century BC. Among the preparations for the overthrow had been the winning over of popular support.
One day, Tang was having a walk in the open country. He saw a man catching birds with a big net spread in a box-like and mumbling: "Come on, birds! Come into my net. All of you, whether you are flying high or low, east or west. Come into my net!"
Tang walked over and said to the man, "This method is ruthless! You'll spare no birds this way!" With these words, he cut the net down on three sides. Then he murmured in a light voice as if praying: "Oh, birds! Fly to the left or right as you like. And if you're really tired of your life, come into this net!"
When chiefs of other tribes heard about this, they were all moved. They said, "Tang is a good king indeed. He is so kind even to birds and beasts. He must be more merciful to human beings." And very soon, about forty tribes pledged allegiance to Tang.
From that story came the idiom "Open the net on three sides". Later, people changed it into "Give the wrong-doer a way out."， indicating to be lenient to the wrong-doers.

网开一面
从大禹到桀，夏朝一共持续了四百多年的历史。
那是在公元前十八世纪。桀是个极端残暴，放荡的人。他激起了人民的极度不满。部落商的领袖汤利用这个形势，推翻了夏朝，并在公元前十七世纪早期建立了商朝。在准备这场推翻夏朝的行动中，汤赢得了广泛的支持。
一天，汤在一片开阔的田野里散步。他看见一个人正在捕鸟。那人支开一张像笼子般的大网，喃喃的说："来吧，鸟儿们！飞到我的网里来。无论是飞得高的还是低的，向东还是向西的，所有的鸟儿都飞到我的网里来吧！"
汤走过去对那个人说："你这种方法太残忍了！这样作你连一只鸟也不放过！"
一边说着，汤砍断了三面网。然后，像做祈祷那样，他轻轻的低声说道，"哦，鸟儿们，喜欢向左飞的，就向左飞；喜欢向右飞的，就向右飞；如果你真的厌倦了你的生活，就飞入这张网吧！"
其它部落的首领得知这件事后都非常感动。他们说："汤真是一位贤王啊。他对鸟兽都如此仁慈，何况是对人呢？" 不久就有四十多个部落宣誓效忠汤。
"网开三面"这个成语就是由此而来的。后来，人们把它改为"网开一面"，表示宽容的对待做错事的人。