This is from the fourteen mindfulness trainings from Thich Nhat Hanh, also called Thay. You can see them and more related information on the Deer Park Monastery website.
http://www.deerparkmonastery.org/mindfulness-practice/the-fourteen-mindfulness-trainings or here: http://www.mindfulnessbell.org/14trainings.htm
The Ninth Mindfulness Training: Truthful and Loving Speech
Aware that words can create suffering or happiness, I am committed to learning to speak truthfully and constructively, using only words that inspire hope and confidence. I am determined not to say untruthful things for the sake of personal interest or to impress people, nor to utter words that might cause division or hatred. I will not spread news that I do not know to be certain nor criticise or condemn things of which I am not sure. I will do my best to speak out about situations of injustice, even when doing so may threaten my safety.
