The Monkeys Paw

From the text:

"If you've had your three wishes, it's no good to you now, then, Morris," said the old man at last. "What do you keep it for?"
The soldier shook his head. "Fancy, I suppose," he said, slowly. "I did have some idea of selling it, but I don't think I will. It has caused enough mischief already. Besides, people won't buy. They think it's a fairy tale; some of them, and those who do think anything of it want to try it first and pay me afterward."