Thor's daughter, Þrúðr, was promised to Alvíss. However, Thor did not want Alviss married to his daughter, so he devised a plan to stop Alvíss from doing so. He told Alvíss that, because of his small height, he had to prove his wisdom. Alvíss agreed. Thor made the tests last until after the sun had risen. Alviss, because he was a dwarf, was petrified when he was exposed to sunlight, and Þrúðr remained unmarried.