Heimskringla Taught Powers

He became very famous because of these powers. His
enemies feared him, but his friends trusted him and believed in his power
and in him. And he taught most of his skills to his sacrificial priests. They
were next to him in all lore and magic. And yet many others learned much
of it, and from there heathendom spread widely and lasted for a long
time. And people worshipped Óðinn and the twelve rulers and called them
their gods and believed in them long afterwards.


- Heimskringla, Ynglinga Saga, Chapter 7