This expression derives from the Gróttasöngr or the Song of Grótti, an old Norse poem:
King Fróði visited Sweden and its king Fjölnir, and from Fjölnir he bought two female slave giantesses named Fenja and Menja who were big and strong. In Denmark, there were two big mill stones which were so big that no man was strong enough to use them. However, the man who ground them could ask them to produce anything he wished. This mill was called "Grótti" and it had been given to Fróði by Hengikjopt.
Fróði had Fenja and Menja tied to the mill and asked them to grind gold, peace and happiness for himself. Then he gave them neither rest nor sleep longer than the time of a song or the silence of the cuckoo. In revenge Fenja and Menja started to sing a song named the "song of Grótti" (the poem itself) and before they ended it, they had produced a host led by a sea-king named Mysing. Mysing attacked Fróði during the night and killed him, and left with rich booty. This was the end of the Fróði peace.