Gróttasöngur
Gróttasöngur, or the Song of Grótti, is a poem found in the Poetic Edda, a collection of Old Norse heroic and mythological poems. The poem is attributed to the dwarf-king Grótti and recounts his and his fellow dwarf, Fenni's, forced labor grinding millstones. These millstones, imbued with magical properties, were commanded to grind out wealth and fortune. However, the millstones became so powerful that they ground out an entire kingdom, and eventually, in their insatiable grinding, they even ground themselves to pieces.
The narrative describes the immense strength and tireless effort required by the dwarves to operate the mill.