The Hávamál Norse Mythology Book – Verse 139

I ween that I hung | on the windy tree,

Hung there for nights full nine;

With the spear I was wounded, | and offered I was

To Othin, myself to myself,

On the tree that none | may ever know

What root beneath it runs.

-Hávamál v139, Bellows translation

Verse 139 is important. It begins the last, and most famous group of poems in The Hávamál explaining how Odin (Othin) obtained his magic:

The windy tree: the ash Yggdrasil (literally “the Horse of Othin,” so called be cause of this story), on which Othin, in order to win the magic runes, hanged himself as an offering to himself, and wounded himself with his own spear.

– Notes from Bellows