From “The Elves” in The Original Folk and Fairy Tales of the Brothers Grimm: The Complete First Edition by Jacob and Wilhelm Grimm, translated and edited by Jack Zipes:
“A shoemaker had become so poor that he didn’t have enough leather left for a single pair of shoes. In the evening he cut out the shoes that he planned to work on the next morning. However, when he got up the next day and was about to sit down to do his work, he saw the two shoes already finished and beautifully made, standing on the table. Soon a customer paid so well that the shoemaker could purchase enough leather for two pairs of shoes, which he cut out that evening. The next morning when he once again wanted to sit down and work, they were already finished, just as the pair had been the other day. Now he was able to purchase enough leather for four pairs of shoes from the money he received from the two pairs. And so it went. Whatever he cut out in the evening was finished by morning, and soon he was a well-to-do man again.
“Now one evening right before Christmas after he had cut out many shoes and wanted to go to bed, he said to his wife: ‘We should stay up one time and see who does our work in the night.’
“So they lit a candle, hid themselves in the corner of the room behind the clothes that had been hung up there, and watched closely. At midnight two cute little naked men came and sat down at the workbench, took all the cutout pieces of the shoes, and worked so swiftly and nimbly that the shoemaker could not take his eyes off them. Indeed, they were incredibly fast, and he was amazed. They didn’t stop until they had finished the work on all the shoes….
“Then they scampered away, and it wasn’t even day yet….“