Who said "Gratitude is what weak people feel."?

This quote is attributed to Nelson Muntz.

Gratitude is what weak people feel. - Nelson Muntz

"Gratitude is what weak people feel."

Nelson Muntz Gratitude

"Ha-ha!"

"Your tears of unfathomable sadness!"

"I'm gonna enjoy this, Bart. I'm gonna enjoy this a lot."

"Eat my shorts, Simpson!"

"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"