I just read a great article by Harvey Mackay, with a story about Socrates:

One day in ancient Greece an acquaintance met the great philosopher Socrates and said,

"Socrates, do you know what I just heard about your friend?"

"Hold on a minute," Socrates replied. "Before telling me anything I’d like you to pass a little test. It’s called the Triple Filter Test."

"Triple Filter?"

"That’s right," Socrates continued. "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. The first filter is Truth. Have you made absolutely sure that what you are about to tell me is true?"

"No," the man said, "actually I just heard about it and…"

"All right," said Socrates. "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?"

"No, on the contrary…"

"So," Socrates continued, "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?"

"No, not really."

"Well," concluded Socrates, "if what you want to tell me is neither true nor good nor even useful, why tell it to me at all?"

You can read the full article here.

It reminds me of a piece of advice that someone told me or I read in the past, it was quite simple. When someone comes to you and complains about another person or talks about that person, your answer should always be simple and to the point:

‘Wow. What did he (the person being discussed) say when you told him/her?’

In other words, if you have something to say, say it to the person who can benefit the most – the person you are talking about.