The elders and venerable ones have offered this reflection as a reminder for the cultivation of mindfulness: “When dwelling alone, guard well your thoughts; when dwelling among companions, guard well your words.”
Even speech that is well-intentioned, when offered without sufficient care and circumspection, may at times give rise to misunderstanding. How much more so, then, when words are spoken without refinement or grace — discord and friction shall arise with ease.
Should one fail to guard one’s speech, those who were once companions may be transformed into adversaries, and in the wake of such estrangement, suffering and mutual harm shall inevitably follow.
Let it therefore always be held in remembrance: “There is nothing that can inspire and uplift the human spirit as swiftly as the spoken word — and equally, there is nothing that can crush and diminish that same spirit as suddenly as the spoken word.”
It is for this very reason that the Perfectly Enlightened One, the Lord Buddha, gave this solemn admonishment: “One should utter only words that are beautiful and wholesome; one should never give voice to words that are base and harmful. Wholesome speech brings purpose and benefit to fulfilment, whilst one who utters harmful words shall come to suffer.”
From the book Siṅgālovāda Sutta (Padet Dattajeevo), page 103


