Turn the other cheek is a famous phrase taken from the Sermon on the Mount in the Christian New Testament. This passage is viewed as promoting nonresistance, pacifism or nonviolence.
Jesus- "You have heard that it was said, 'An eye for an eye, and a tooth for a tooth.' But I tell you, do not resist an evil person. If someone strikes you on the right cheek, turn the other cheek. And if someone wants to sue you and take your tunic, let him have your cloak as well. If someone forces you to go one mile, go with him two miles. Give to the one who asks you, and do not turn away from the one who wants to borrow from you."