Ragnar asks Athelstan to teach him one of his prayers on the season finale of Vikings.
Ragnar and Horrik head back to Kattegat on the season 2 finale of Vikings.

Vikings Season 2 Episode 10 Quotes

Horik: Forgive me Floki. I know I should trust you but I need proof.
Floki: Proof?
Horik: Yes, prove to me I can trust you. Prove to me you are on my side.
Floki: How can I prove it?
Horik: Kill someone. Someone who matters.

I've seen you pray to your God. Will you teach me one of your prayers so I can learn?