Who said "A man must know who he is. That's the first rule."?

This quote is attributed to Theon Greyjoy.

A man must know who he is. That's the first rule. - Theon Greyjoy

"A man must know who he is. That's the first rule."

Theon Greyjoy Truth

"I am the Prince of Winterfell. I have no need to prove myself to anyone."

"What is dead may never die."

"You can't marry her. You're promised to me."

"I'm a Greyjoy. We do not sow."

"Lucy, you got some 'splainin' to do!"

"You must always be honest with the people you love."

"Truth always comes out in the end."

"Honesty is always the best policy."