It's pretty common, when you encounter a troll in a fantasy video game or fantasy table-top RPG the troll is able to regenerate from damage. Typically trolls only have 1 weakness; fire, which somehow stops the regenerative process.
I've been curious where this idea of trolls being able regenerate originated from. Is there a specific novel or possibly an old fairy tale that tells of a regenerating troll? Does this original text also talk about Troll's weakness to fire, or was that established later in over-all "troll lore"?