Who said "The work of peace is harder than the work of war."?

This quote is attributed to Aquaman (DCEU).

The work of peace is harder than the work of war. - Aquaman (DCEU)

"The work of peace is harder than the work of war."

Aquaman (DCEU) Work

"I'm a king. Kings don't run."

"The surface world has much to learn about respect."

"My people have watched you from below for centuries."

"I didn't come here to fight you."

"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."