Who said "The Dothraki do not understand mercy, only respect."?

This quote is attributed to Drogo.

The Dothraki do not understand mercy, only respect. - Drogo

"The Dothraki do not understand mercy, only respect."

Drogo Justice

"I am the stallion who mounts the world"

"A Dothraki hears a word and takes it as a command"

"You are of my blood. That is enough"

"I will take what is mine with fire and blood"

"Justice must always prevail."

"You think I'm just some animal?"

"Fighting for what's right never gets easier."

"Justice is worth fighting for."