“Once upon a time there was a man and he was very poor.”
A poor man observes robbers who enter into a mountain. Uses, like them, the words “Open up” and gets gold from the mountain. His rich brother tries to do the same thing but is killed. The rich brother lends his money scales to the poor brother; a piece of money remains in the scales and thus betrays the secret. When he is in the mountain he forgets the formula for opening it.