Who said "I've seen too much to back down now."?

This quote is attributed to War Machine.

I've seen too much to back down now. - War Machine

"I've seen too much to back down now."

War Machine

"Next time, maybe you'll listen when I tell you something."

"I'm a soldier. That's what I do."

"You think you're the only one with something to prove?"

"I follow orders. That's the difference between us."