Who said "I understand duty. It is all I have ever known."?

This quote is attributed to Grey Worm.

I understand duty. It is all I have ever known. - Grey Worm

"I understand duty. It is all I have ever known."

Grey Worm Work

"I am Grey Worm. I have no name."

"Unsullied do not fear death."

"We are the dragons' soldiers."

"A soldier's duty is to obey."

"Hard work never killed anybody."

"Work with purpose and integrity."

"Hard work pays off in the end."

"A man's gotta do what a man's gotta do."