Here are my favorites on the topic:
“Whoever says to the guilty ´You are innocent,´ peoples will curse him and nations denounce him. But it will go well with those who convict the guilty, and rich blessing will come upon them.” Proverbs 24:23-25
“Woe unto them that call evil good, and good evil; that put darkness for light, and light for darkness; that put bitter for sweet, and sweet for bitter!” Isaiah 5:20
Silence in the face of evil is itself evil: God will not hold us guiltless. Not to speak is to speak. Not to act is to act.
—Dietrich Bonhoeffer
Excellent!