The definition of gheeba is to make mention of your brother/sister who is not present saying something which they would not like were it to reach them. This may include mentioning some physical defect, a slur against his/her background, family or his/her character. It makes no difference whether it is a true statement or not. The proof for this is from the hadith:
مسلم:
عَنْ أَبِي هُرَيْرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ أَتَدْرُونَ مَا الْغِيبَةُ قَالُوا اللَّهُ وَرَسُولُهُ أَعْلَمُ قَالَ ذِكْرُكَ أَخَاكَ بِمَا يَكْرَهُ قِيلَ أَفَرَأَيْتَ إِنْ كَانَ فِي أَخِي مَا أَقُولُ قَالَ إِنْ كَانَ فِيهِ مَا تَقُولُ فَقَدْ اغْتَبْتَهُ وَإِنْ لَمْ يَكُنْ فِيهِ فَقَدْ بَهَتَّهُFrom Abu Huraira that Allah's Messenger (sas) said: "Do you know what al-gheeba is?" They said, "Allah and His Messenger know best." He (sas) said, "To make mention of your brother with that which he dislikes." They said, "How about if my brother actually has what I have said about him? He (sas) said, "If he has what you have said about him, then you have committed gheeba and if not, then you have committed buhtaan (slander).
KNOW that anything which is understood to be negative falls under gheeba whether it is verbal, by signs or motions or written. One of the most evil forms of gheeba is from the ostentatious who put up a show of piety. For example, when another is mentioned in their presence, they say something like: "Al-hamdu lillahi who did not test us with going to the rulers or exerting ourselves in seeking the paltry things of this life." Or: "I seek refuge in Allah from lack of shame." Or: "I ask Allah for health (soundness)." The authors of such statements combine detracting from the one mentioned with praising themselves. Or, one of them may say: "Poor man, he has been tested with a serious affliction. May Allah forgive us and forgive him." In this way, he puts up a show of du'a, attempting to disguise his real intention.
KNOW that anyone who listens to gheeba is a partner (participant) in it. His sin is no less than the other unless he condemns it with his tongue. If he fears for himself from the other, he must at the least condemn it with his heart and if he is able to stand and leave or to cut off the talk and change the subject, then he must do so. The Prophet (sas) said:
أحمد:
مَنْ أُذِلَّ عِنْدَهُ مُؤْمِنٌ فَلَمْ يَنْصُرْهُ وَهُوَ قَادِرٌ عَلَى أَنْ يَنْصُرَهُ أَذَلَّهُ اللَّهُ عَزَّ وَجَلَّ عَلَى رُءُوسِ الْخَلَائِقِ يَوْمَ الْقِيَامَةِ"Whoever witnesses the humiliation of a believer and does not come to his defense, though he was able to do so will be humiliated by Allah Mighty and Great in front of His creation on the day of Qiyama." (It has a weak narrator)
أحمد:
من حَمَى مُؤْمِنًا مِنْ مُنَافِقٍ يَعِيبُهُ بَعَثَ اللَّهُ تَبَارَكَ وَتَعَالَى مَلَكًا يَحْمِي لَحْمَهُ يَوْمَ الْقِيَامَةِ مِنْ نَارِ جَهَنَّمَ وَمَنْ بَغَى مُؤْمِنًا بِشَيْءٍ يُرِيدُ بِهِ شَيْنَهُ حَبَسَهُ اللَّهُ تَعَالَى عَلَى جِسْرِ جَهَنَّمَ حَتَّى يَخْرُجَ مِمَّا قَالَ"Whoever protected a believer from a hypocrite who scandalizes him, Allah the Blessed and High will assign an angel who will protect his flesh on Qiyama from the fires of Jahannam. And whoever seeks a way to scandalize a believer, Allah Most High will hold him on the bridge over the fire until he removes himself from what he said." (It has a weak narrator.)
Umar ibn Utbah saw his master with another man speaking about a third. He said to him, "Woe to you, guard your hearing against listening to evil speech just as you guard your self against engaging in it. The listener is the partner of the speaker. He simply looked for the worst thing in his baggage and dumped it in to yours. And, if the words of the ignorant one were put back in the mouth of their author, the one who returned them would rejoice just as the on who spoke them would suffer."
Reference also, the many hadith about the right of every Muslim over every other Muslim which preceded in the chapter about companions.
To calm his rage or feelings of hurt. The other one may have done something which caused feelings rage or hurt. Every time he feels those feelings, he seeks some "relief" by backbiting the other. If the original hurt was itself gheeba, this clearly becomes a vicious circle with each one imagining they are "justified" in what they are doing.
Sticking with "the crowd" and pleasing his companions. Even if he sees them gorging themselves on the honor of others, he fears that were he to warn them and condemn their actions that they might find that burdensome and reject his friendship. And so, he helps them in what is wrong and mistakenly thinks that in so doing he is maintaining good relations.
A need to raise one's status by lowering that of others. So, one may say about another that he is ignorant or his understanding is weak - not in order to warn others about some deviation, but rather just with intention of implying that he himself is more knowledgeable and better guided than the one being mentioned. Similarly, he may be envious of one who is loved and respected by people and so he speaks ill of him in order to put an end to that.
"Joking around". And so he mentions another in a way which makes people laugh and/or my imitating or mimicking him.
As for the cure for gheeba, first and foremost is for the backbiter to remember that he is exposing himself to the wrath of Allah and His contempt and displeasure. Also, he should remember that his good deeds will be transferred to the victim of his tongue because of his act and that if he has no good deeds or they run out, that the sins of his victim will be transferred to his scale. Anyone who truly remains conscious of this will not allow his tongue to run rampant with gheeba. And when it occurs to him to engage in gheeba, he should ponder his/her own faults, busy himself with rectifying those faults and feel shame that he should engage in mentioning the faults of others while he still has his own. As one poet put it:
فان عبت قوما بالذي فيك مثله فكيف يعيب الناس من هو أعور
و ان عبت قوما بالذي ليس فيهم فذلك عند الله والناس أكبرSo, if you scandalize people with that which resembles something in yourself
How does a one-eyed man delve into the shortcomings of others?And, if you scandalize people with something of which they are innocent,
That is, before Allah and before the people more heinous.
Even if he believes himself to be free of faults, he should busy himself with giving thanks to Allah for this great gift and not pollute himself with the ugliest of all faults - al-gheeba. Also, just as he would not be pleased if others were to speak ill of him, so he should not be pleased for others to be victims of the same coming from him.
Next, look to the cause or reason which is pushing one in the direction of gheeba and then address the removal of this cause. If the cause is anger, there is a whole chapter coming on its cure. The cure for the desire for conformity (pleasing friends) is cured by remembering that Allah is angry with one who seeks the agreement of people by engaging in that which Allah dislikes. Rather, he should more appropriately be angry with his "friends" who are engaging in such things.
Gheeba can be committed by the heart when one thinks ill of another Muslim. Allah said:
الحجرات:
يَاأَيُّهَا الَّذِينَ ءَامَنُوا اجْتَنِبُوا كَثِيرًا مِنَ الظَّنِّ إِنَّ بَعْضَ الظَّنِّ إِثْمٌ وَلَا تَجَسَّسُوا وَلَا يَغْتَبْ بَعْضُكُمْ بَعْضًا أَيُحِبُّ أَحَدُكُمْ أَنْ يَأْكُلَ لَحْمَ أَخِيهِ مَيْتًا فَكَرِهْتُمُوهُ وَاتَّقُوا اللَّهَ إِنَّ اللَّهَ تَوَّابٌ رَحِيمٌ(12){O you who believe, steer clear of most assumption for some assumption is surely sinful. And do not spy on one another nor backbite one another. Does one of you like that he should eat his brother's flesh after he has died? You would surely hate that. And beware of Allah, verily Allah is Accepting, Merciful.}
Adh-dhann (assumption or suspicion) is that to which that heart is inclined to believe. It is not allowed for you to think ill of another Muslim unless it revealed to you in a manner which leaves NO room for doubt or other interpretation. If a trustworthy individual informs you of it (in a manner which is allowed, of course) and you are inclined to believe him, they you have an excuse. For if you discredit the one who has informed you, then you have thought ill of him and it is not desirable to have good thoughts about one by having bad thoughts about the other. Rather, you should look into it. Is there any enmity or envy between these two? This could be the actual cause of the accusation.
Whenever any bad or suspicious thought occurs to you regarding another Muslim, you should exert yourself more and watching out for him and making du'a for him. This is the best way to defeat Shaitaan and get him out of your business. Next time, Shaitaan will be afraid to suggest this evil for fear of the opposite of his desired result - that instead of creating enmity and division among the Muslims, he has in fact caused more devotion to caring for one another and making du'a for one another. All should ponder this, but few will ever attain it! Allah said:
فصلت:
وَمَنْ أَحْسَنُ قَوْلًا مِمَّنْ دَعَا إِلَى اللَّهِ وَعَمِلَ صَالِحًا وَقَالَ إِنَّنِي مِنَ الْمُسْلِمِينَ(33)وَلَا تَسْتَوِي الْحَسَنَةُ وَلَا السَّيِّئَةُ ادْفَعْ بِالَّتِي هِيَ أَحْسَنُ فَإِذَا الَّذِي بَيْنَكَ وَبَيْنَهُ عَدَاوَةٌ كَأَنَّهُ وَلِيٌّ حَمِيمٌ(34)وَمَا يُلَقَّاهَا إِلَّا الَّذِينَ صَبَرُوا وَمَا يُلَقَّاهَا إِلَّا ذُو حَظٍّ عَظِيمٍ(35){And who is better in speech than one who calls to Allah, acts righteously and says, "I am among those who submit." (33) And act of good is not equal to an act of bad. Repel with that which is better. Then, you will see the one with whom there was enmity as if he is the dearest of friends. (34) And none shall encounter this except those who are patient and none shall encounter this except those who are most fortunate indeed. (35)
After all this it becomes clear to you that the fault is real and verified in your brother/sister, then proceed to find a way to advise him/her IN SECRET, never in front of others.
KNOW that one of the evil results of thinking ill of others is at-tajassus (spying on one another). The heart is not satisfied with suspicion and wants to know more and be sure and so it causes one to engage in tajassus which Allah has forbidden because it leads to the destruction of the privacy of Muslims.