emphatically Ghibat/ backbiting is denounced in Islam.

Originally Posted by Qur'an, Surat Al-Hujurat (Chapter 49), Verse 12

Sahih International [49:12]
O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin. And do not spy or backbite each other. Would one of you like to eat the flesh of his brother when dead? You would detest it. And fear Allah ; indeed, Allah is Accepting of repentance and Merciful.

Originally Posted by Sahih Muslim, Book 32, Chapter 18, Hadith Number 6265

Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: 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.

Sahih Muslim, Book 32, Chapter 18, Number 6265

Originally Posted by Sahih Muslim, Book 1, Hadith Number 0075

It is reported on the authority of Abu Huraira that the Messenger of Allah (may peace be upon him) observed: He who believes in Allah and the Last Day should either utter good words or better keep silence...

Sahih Muslim, Book 1, Number 0075