Intelligent Person's. . .

"The intelligent person's tongue is behind his heart - when he wants to speak,he first thinks. If [his words] will be in his favour, he says them and if they'regoing to be against him, he does not speak. The ignorant persons heart is behind his tongue - when he merely thinks of saying something, he says it,whether it is for or against him."
[Hasan Al Basari]