In ancient times, there was a prime minister named Shang Yang in the State of Qin. He was held in high regard by the King. In the year 359 BC, he wanted to reform the system politically in order to promote economic development. But he was afraid that the people would not believe local authorities. So he came up with an idea.
One day, he had a 10-meter-long pole erected at the south gate outside the capital. Then he told the crowd that whoever successfully carried the pole to the north gate would be awarded 10 ounces of silver. Everyone was astonished, but nobody dared to try. After seeing their lack of response, Shang Yang raised his voice and said, "Anyone who carries the pole to the north gate will get 50 ounces of silver." A brave man did it and was immediately given 50 ounces of silver. Others in the crowd then regretted not trying.
In this way, Shang Yang achieved his goal. Soon after, the State of Qin became the strongest country around.
Today, people use the phrase to reconfirm that one can keep his promise.