In the discourse on mindfulness, the Buddha says we can be mindful while talking or keeping silent. What does he mean? Of course, talking involves thinking and verbalizing, that is, moving of our mouth and tongue to produce sound and words. So we can be mindful of our lips moving and the thoughts that arise in our mind as we speak. But I think what is most important here is to be mindful of whether our speech is wholesome or not, whether it falls within Right Speech of the Noble Eightfold Path.
Right speech is speaking the truth, not lying, misrepresenting, misleading, or deceiving. A good motivation when speaking is important. This means one should speak with goodwill, not ill-will. One should be honest and sincere in what one says.
Right speech is not slandering or speaking maliciously. As far as possible one should try to promote concord, understanding and friendship between two parties rather than cause misunderstanding, discord and animosity. Right speech is not speaking harshly, in anger, or with intent to hurt. Remember that though sticks and stones may break our bones, words can do far worse: they can break our hearts. So one should take care to speak gently, kindly, with the best of intentions, considering the sensitivity and “hurtability” of others.
Right speech is not gossiping and taking delight in speaking ill about others. It is not speaking frivolously and nonsensically about things which are of no benefit to the hearer. Right Speech is speaking about things which are important and beneficial. It is about giving wise counsel and reminding each other of the need to practise the Dhamma in order to gain liberation from samsaric suffering.
Right speech is not speaking with envy and jealousy but with magnanimity, being able to rejoice over and be happy for the wholesome deeds and accomplishments of others.
Right speech does not mean we cannot criticise or admonish or point out the faults of others. But it does mean that we must be careful to do so with objectivity, fairness, sincerity and good intentions. We must be careful to speak without anger, hatred, illwill, malice, and prejudice. We must be careful not to become overly critical, judgmental or fault-finding. We must be able too, to see the good in others, to be balanced in our judgment or assessment of others.
Having said all this, we do agree it is not easy to practise Right Speech all the time. Many a time we may speak unskilfully or frivolously and unnecessarily. Many a time we may lose our cool and speak in anger or irritation, snapping or hitting out at another. Many a time we may be speaking just to fill the void of silence. And many a time, too, it may have been better for us to keep noble silence and maintain our mindfulness and equanimity in that silence.
Practising Right Speech is a great challenge; it is something we have to constantly practise and improve upon.