Who said "Kindness is a sign of weakness only to the weak."?

This quote is attributed to Avengers Tony Stark.

Kindness is a sign of weakness only to the weak. - Avengers Tony Stark

"Kindness is a sign of weakness only to the weak."

Avengers Tony Stark Kindness

"I'm not a genius. I'm just a man in a suit."

"Sometimes you gotta run before you can walk."

"The world's always ending. The end of the line, the end of the road."

"I have a plan. Attack."

"A good man treats his wife with respect."

"Kindness always comes back around."

"The power of a smile can change everything."

"Kindness is weakness to some. Not to me."