by Brother Ismail
The Muslim has to guard his tongue and avoid things that have been forbidden. Among these forbidden things which people take often lightly are gheebah (backbiting), buhtaan (slander) and nameemah (malicious gossip).
Allaah says (interpretation of the meaning):
“neither backbite one another. Would one of you like to eat the flesh of his dead brother? You would hate it (so hate backbiting). And fear Allaah. Verily, Allaah is the One Who forgives and accepts repentance, Most Merciful”
Gheebat (backbiting) is perhaps the most commonly committed sin of the tongue. Most people who are religious conscious would refrain from lying, swearing, slandering, etc. However, even such people invariably become entrapped in the snare of Shaitaan and allow their conversation to drift into gheebat. Indeed only the one who has a firm control of his tongue can be saved from this malady, but what is gheebat? It is thus imperative that Gheebat be accurately identified and recognized in order to be able to refrain from it. The Ahaadith have defined this malady very simply and clearly. It is reported in a hadith that Rasulallah (saw) once inquired of the Sahaba (ra): "Do you know what is gheebat?" "Allah and His Messenger know best," they replied. "To mention something about your brother which he would dislike" Rasulallah (saw) informed them.
A person then asked: "What if this is true?" (That the person being spoken about is actually involved in that sin). The Messenger of Allah (saw) replied: "If it is true then you have indeed backbitten about him. But if it is untrue, then you have slandered him (which is worse)."
Hence to mention anything about a person in his absence which he would dislike is gheebat. The magnitude of the sin, the gravity of this malady could be gauged from the following Ahaadith. Rasulallah (saw) is reported to have said: "Gheebat is worse than zina (adultery)." In another hadith it is reported that there are more than seventy stages of consuming interest, the lowest of which is equivalent to cohabiting with one's mother. To consume one Dirham of interest is worse than committing adultery thirty five times.
However, a sin more severe than interest is the dishonoring of a Muslim (which is a natural consequence of gheebat). (Baiqahi) Engaging in gheebat is also an extremely costly affair. It is reported in a Hadith that on the day of Qiyamah the person who was backbitten about would claim retribution from the one who spoke ill of him. Allah (swt) will compensate the victim by handing over the good deeds (the currency of the Hereafter) of the culprit to him. If the latter has no good deeds to his credit, the sins of the victim would be transferred to him.
Hence the Salah, Sawn, Zakat, Hajj, etc. of a person would all be lost due to gheebat. A tremendous loss indeed! How often do we engage in gheebat, yet regard ourselves as free from this crime? This is due to certain misconceptions. Many people assume that gheebat does not apply if one could mention the same facts about a person in his presence. How often does a person retort: "This is not gheebat. I can say it to his face." This, however, is the deception of Shaitaan. The Ahaadith contain no such restriction which excludes the above from the purview of gheebat.
Likewise many people believe that gheebat only applies if the sin of the spoken person is not known. This is another misconception. If the sin is well known, it is gheebat only, however, if such a sin of a person was discussed which the next person was unaware of, two severe sins have been incurred; one is the sin of gheebat, and the other is the sin of disclosing the fault of another Muslim.
link provided by : http://www.themodernreligion.com/misc/hh/gh-harm.html