Who said "Gratitude is the rarest quality in powerful beings."?

This quote is attributed to Hulk King.

Gratitude is the rarest quality in powerful beings. - Hulk King

"Gratitude is the rarest quality in powerful beings."

Hulk King Gratitude

"I am the king of this place. What are you?"

"Strongest one there is, that's what they call me."

"You are strong. For a small person."

"But I am strongest one there is!"

"Gratitude makes life richer."

"A grateful heart is a happy heart."

"Respect those who came before us."

"Life's greatest treasures are the people we love"