Who said "Death is the only certainty; how we live is the question."?

This quote is attributed to Missandei.

Death is the only certainty; how we live is the question. - Missandei

"Death is the only certainty; how we live is the question."

Missandei Death

"I am Missandei of Naath, interpreter and advisor to the Dragon Queen."

"Daenerys Targaryen chose to free us, not because she needed us, but because it was right."

"Knowledge is power, but wisdom is knowing how to use it."

"I have served many masters, but I chose to serve the Mother of Dragons."

"Death doesn't scare me anymore."

"Death and I are old friends."

"Welcome to my world."

"Death is just the beginning."