What I feel is that sometimes to defend ourselves we do need to speak, it might not be the situations of small argument or a random comment but there are times when it's truly need to reply back to end that conservation because some people who are actually jealous of us or hate us keep on passing sorts of comments to make us feel low, at that time there is need for a powerful line(fitting in that situation suitably) that can make the other person quite and silent forever because sometimes only listening doesn't solve the purpose out!