The Prophet sal Allahu ‘alaihi wa sallam said:
“The believer is not a person who hurts others with words, or curses, or swears, or is foul-mouthed.” [Bukhari]
And:
“Whoever believes in Allah and the Last Day, let his speak good or remain silent.” [Bukhari]
If Imam Bukhari knew a narrator of hadeeth was a liar or untrustworthy, he would be shy and never say so-and-so is a liar but rather he would simply say, “Don’t write his hadeeth or do not narrate anything from him.” However, some other scholars might say of the same person that Bukhari mentioned that “this person is the greatest liar from mankind.”
The son of Imam Ahmed asked his father, why he did not use stronger language against the innovators in his time and he replied:
“O my son, have your ever heard your father say anything bad about anyone?”
Such a beautiful methodology and manner that is lost in our time, where the louder, brasher, more vulgar and obscene is praised and wins the argument as we can see from the shameful displays at the current healthcare reform townhall meetings and in the coarsening of our public discourse.
From the Storehouse: Is Respect Too Much to Ask?
Ify Okoye 
Soooo true. Thank you for this. May Allah(swt) reward you.
Thank you very much for this knowledge, I am definately more mindful now of what comes out of my mouth. My father did always say “if you have nothing good to say, then say nothing” and “the one who does not speak, will not be called to repeat”, how very true-thank you.