During the reign of Song Renzong, an owner of a rice store had a bad business, so he asked a scale builder to make a 15-half-taels scale for him (in ancient times a catty was 16 taels), and promised to give enough money.
This was incidentally heard by the rice store owner’s little daughter-in-law. After he left, the little daughter-in-law told the scale builder:
"My dad was not very clear in his instructions in making the scale just now. He asked you to make a 16-half-taels scale. Thank you in advance and after it is done, I will double the payment to you."
Later, the rice store owner took the scale back to the rice shop, and his business was booming.
Not only customers from the neighboring rice store often visited, but customers from far away also kept coming.
At the end of the year, the owner of the rice shop found that his profit had quadrupled. He proudly said that the secret of his profit was to make half an extra tael for every catty sold.
At this time, the little daughter-in-law got up and told the whole story. The owner suddenly realized and felt extremely ashamed but more grateful and enlightens.