Right Speech involves respect for truth and respect for the welfare for others. It means to avoid lying, to avoid backbiting or slander, to avoid harsh speech, and to avoid idle talk. We have often underestimated the power of speech and tend to use little control over our speech faculty. But we have all been hurt by someone's words at some time of our life, and similarly we have been encouraged by the words of another. It is said that a harsh word can wound more deeply than weapons, where as a gentle word can change the heart and mind of the most hardened criminal. So to develop a harmonious society, we should cultivate and use our speech positively. We speak words which are truthful, bring harmony, kind and meaningful. The Buddha once said 'pleasant speech is sweet as honey, truthful speech is beautiful like a flower, and wrong speech is unwholesome like filth'.
Ven. K.Sri Dhammananda, What Buddhists Believe