Sahih Muslim Book 45, Hadith 91
Do you know what is backbiting? They (the Companions) said: Allah and His Messenger know best. Thereupon he (the Holy Prophet) said: Backbiting implies your talking about your brother in a manner which he does not like. It was said to him: What is your opinion about this that if I actually find (that failing) in my brother which I made a mention of? He said: If (that failing) is actually found (in him) what you assert, you in fact backbited him, and if that is not in him it is a slander.
Charity does not decrease wealth, no one forgives another except that Allah increases his honor, and no one humbles himself for the sake of Allah except that Allah raises his status.
The servant (whose fault) Allah conceals in this world, Allah would also conceal (his faults) on the Day of Resurrection.