Here is a useful advice via the blog Hubb-e-Ilahi.
Filter TestRasul Allah (sal Allahu alaihi wa sallam) said: “Keep away from ill-thinking/suspicions because ill-thinking is the greatest falsehood.” [Sahih Bukhari]
Commentary: During the Abbasid period one of the scholars in Baghdad was greeted by an acquaintance who said, "Do you know what I just heard about your friend?"
Scholar: "Hold on a minute, before telling me anything I'd like you to pass a little test. It's called the Triple Filter Test."
The Man: "Triple Filter Test?"
Scholar: "That's right, before you talk to me about my friend it might be a good idea to take a moment and filter what you're going to say. That's why I call it the triple filter test. The first filter is Truth. Have you made absolutely sure that what you are about to tell me is true?"
The Man: "No, actually I just heard about it and ..."
Scholar: "All right, so you don't really know if it's true or not. Now let's try the second filter, the filter of Goodness. Is what you are about to tell me about my friend something good?"
The Man: "No, on the contrary..."
Scholar: "So, you want to tell me something bad about him, but you're not certain it's true. You may still pass the test though, because there's one filter left: The filter of Usefulness. Is what you want to tell me about my friend going to be useful to me?"
The Man: "No, not really."
Scholar: "Well, if what you want to tell me is neither true nor good nor even useful, why tell it to me at all?"
Allah (subhana wa ta’ala) asks us: "O you who believe! Avoid much suspicion, indeed some suspicions are sins. And spy not, neither backbite one another. Would one of you like to eat the flesh (meat) of his dead brother? You would hate it (so hate backbiting). And fear Allah. Verily, Allah is the One Who accepts repentance, the Most Merciful." [Qur'an 49:12]
Let's pass our intended speech through the triple filter test before we madly utter our every thought. And lets subject others to the triple filter test too before we hear any number of damaging things from them.