Who said "The most important thing in life is how you treat people."?

This quote is attributed to George Costanza.

The most important thing in life is how you treat people. - George Costanza

"The most important thing in life is how you treat people."

George Costanza Philosophy

"I'm out there Jerry, and I'm lovin' every minute of it."

"These pretzels are making me thirsty."

"Master of my domain."

"It's not a lie if you believe it."

"I've seen the worst humanity has to offer."

"Sometimes I wonder if the world is worth saving."

"Every choice shapes our destiny."

"Order is the foundation of a good life."