Who said "I've learned that mercy is a weakness I can't afford."?

This quote is attributed to Frank Castle.

I've learned that mercy is a weakness I can't afford. - Frank Castle

"I've learned that mercy is a weakness I can't afford."

Frank Castle Wisdom

"Punishment is a language they understand."

"I'm not a hero. I'm a tool, sharpened and aimed."

"The only way to stop evil is to be better at it than they are."

"Mercy is for the living. The dead don't care."

"I'm not angry, I'm just disappointed."

"The best things in life are free."

"You can't have everything in life, but you can have what matters most."

"A woman's intuition is rarely wrong."