The true Muslim does not gossip or backbite about his brothers and friends, or backbite against them. He knows that gossip is haram, as the Qur'an says:
“...Nor speak ill of each other behind their backs. Would any of you like to eat the flesh of his dead brother? Nay, you would abhor it. But fear Allah: for Allah is Oft Returning, All Merciful.” (Qur'an, Surah Al-Hujurat, 49:12)
The true Muslim who is infused with Islamic teachings and manners will be horrified by the depiction given in the Qur'an of one who gossips as being like one who eats the flesh of his dead brother. This will deter him from gossiping and, if he is guilty of this sin, he will hasten to repent sincerely, as indicated at the end of the ayah quoted. He will then restrain his tongue and speak only good of his brother, remembering the words of the Prophet (sallAllahu ‘alaihi wa sallam):
“Do you know what gossip is" They said, ‘Allah and His Messenger know best.' He said, “It is your saying about your brother something which he dislikes.” He was asked, ‘What do you think if what I say about my brother is true’ He said, “If it is true then you have gossiped about him, and if it is not true then you have slandered him.”
The true Muslim avoids the sin of gossiping directly or indirectly, abhorring the idea of being one who eats the flesh of his dead brother and fearing lest his tongue leads him to Hell. This is made clear by the Prophet's warning to Mu'adh, when he took hold of his tongue and said, "Restrain this." Mu'adh said, "O Prophet of Allah, will we be responsible for what we say?" The Prophet (sallAllahu ‘alaihi wa sallam) said, "May your mother be bereft of you! Is there anything that causes people to be thrown in Hell on their faces (or he said: on their noses) but the harvest of their tongues?" 
Gossip is a bad characteristic which does not befit a real man. Rather it is a feature of two-faced cowards who look like men, those who gossip to people about their brothers and friends, then when they meet them they smile warmly and make a display of friendship. Hence the true Muslim should be the furthest removed from gossip and fickleness, because Islam has taught him to be a real man, to be straightforward and to fear Allah in Allah's words and deeds. It has made him thoroughly despise hypocrisy and fickleness. The two-faced person is regarded as being one of the worst people in the sight of Allah, as the Prophet (sallAllahu ‘alaihi wa sallam) says:
“You will find among the worst people in the sight of Allah on the Day of Resurrection, the one who is two faced, who approaches some people in one way and others in another.”
The true Muslim is straightforward, never two-faced. He meets all people with a friendly, smiling face and does not differentiate between people in the face he presents to them. For he knows that being two- faced is the essence of hypocrisy and that hypocrisy and Islam do not go together. The two-faced person is a hypocrite, and the hypocrites will be in the lowest level of Hell.
By Dr. Muhammad 'Ali al Hashimi
 Reported by Muslim
 Reported by al-Tirmidhi, who said it is a hasan sahih hadith.
 Reported by Bukhari, Muslim, et al