The Prose Edda 1.23

"The third among the Æsir is he that is called Njördr: he dwells in heaven, in the abode called Nóatún. He rules the course of the wind, and stills sea and fire; on him shall men call for voyages and for hunting. He is so prosperous and abounding in wealth, that he may give them great plenty of lands or of gear; and him shall men invoke for such things. Njördr is not of the race of the Æsir: he was reared in the land of the Vanir, but the Vanir delivered him as hostage to the gods, and took for hostage in exchange him that men call Hœnir; he became an atonement between the gods and the Vanir. Njördr has to wife the woman called Skadi, daughter of Thjazi the giant. Skadi would fain dwell in the abode which her father had had, which is on certain mountains, in the place called Thrymheimr; but Njördr would be near the sea. They made a compact on these terms: they should be nine nights in Thrymheimr, but the second nine at Nóatún. But when Njördr came down from the mountain back to Nóatún, he sang this lay:

Loath were the hills to me, I was not long in them, Nights only nine; To me the wailing of wolves seemed ill, After the song of swans.

Then Skadi sang this:

Sleep could I never on the sea-beds, For the wailing of waterfowl; He wakens me, who comes from the deep— The sea-mew every morn.

Then Skadi went up onto the mountain, and dwelt in Thrymheimr. And she goes for the more part on snowshoes and with a bow and arrow, and shoots beasts; she is called Snowshoe-Goddess or Lady of the Snowshoes. So it is said: :Thrymheimr 't is called, :where Thjazi dwelt, ::He the hideous giant; :But now Skadi abides, :pure bride of the gods, ::In her father's ancient freehold.