Thrud ("Strength") is the daughter of Thor and Sif. Some of the gods had promised to marry her to the dwarf Alvis, if he would forge weapons for them. Thor, however, did not like this arrangement and felt that a dwarf made an inappropriate son-in-law. He therefore devised a test of knowledge to prevent this marriage. Alvis had to prove that his great wisdom made up for his small stature. Thor prolonged the test until sunrise and Alvis, still caught up in the test, was touched by the rays of the sun and was turned to stone.