Defamation is a restricted form of speech under the Sharia, and has been tackled at length in the Sharia literature as shall be elaborated below.
Definition and Scope
The equivalent Arabic term for defamation is tashhi̅r. Literally, Shahara is a base form Arabic verb meaning to make something manifest or to expose it to the public. In the technical sense, tashhi̅r bears considerable similarity to its linguistic meaning as it may be collectively defined as exposing someone to the public by virtue of an act, attribute or vice that might disgrace him. Thus, defamation from an Islamic perspective means to expose someone to the public. Defamation may be done rightfully, such as in certain cases of executing legal penalties, or unrightfully, as in buhta̅n (slander), as shall be elaborated below.
The normative Sharia ruling concerning defamation is prohibition. This fact is evidenced by the verse where Allah declares: "There is painful punishment in this world and the next for those who like that immorality should spread among the believers." Commenting on this verse, Ibn Kathi̅r states that the warning mentioned in this verse is a disciplinary measure taken against those who hear some offensive speech and then "reiterate" what they have heard, making it spread and circulate.
Another piece of evidence that may be used in support of the prohibition of this behavior is the hadith where the Prophet commands: "Don't nurse malice against one another, don't nurse aversion against one another and don't be inquisitive about one another (tajassasu, taḥassu) and don't outbid one another (with a view to raising the price) and be fellow-brothers and servants of Allah." Ibn Ḥajar commented that the phrase "Wala tajasssu, wla taḥassau" establishes a proscription of following and exposing people's faults and weaknesses.
In another hadith, the Prophet warns: "He who publicizes a (malice) speech will have his misdeeds publicized by Allah. And if anyone makes a hypocritical display (of his deeds) Allah will make a display of him." Ibn Ḥajar explains that the first part of this hadith means that he who hears of people's defects and then takes them to the public will have his own defects publicized by Allah. The above texts bear explicit warnings of defaming Muslims and exposing their weaknesses, which is indicative of the emphatic prohibition of this form of speech.
Based on the collective Sharia literature concerning the topic in question, the instances of defamation may be classified into several categories as follows:
First: defaming one's self while telling the truth. A person may, for some reason, find it tempting to publicize or disclose an act of disobedience or an illegal act he has committed, such as the case of a person who lies to brag about his skills in fraud or about having illicit sexual affairs with many women. This sort of defamation is forbidden for it is subsumed under a variety of illegal deeds, including: publicizing an immoral act, disdaining the prohibition of committing sins and encouraging the listeners to commit such an illegal acts.
Second, defaming one's self while lying. The same prohibition stated in the first case mentioned above applies to the person who defames himself while lying. Such a person may be motivated to do so for the same reason stated above. In addition to the reasons of prohibition involved in the first case, lying, a sin on its own right, is involved in this case, which adds to the enormity of the act.
Third, defaming one's self before a judge. Sometimes a person who has committed an illegal act may want to confess his crime before a judge during a trial in a court of law. The crime committed in this case is either a violation of a human's right, such as murder, or a violation of God's right, such as fornication. In the former case (i.e. violation of a human's right), he is obliged to give a truthful testimony even at the expense of defaming himself, and defamation is not deemed a criminal act in this case.
Concerning the second case (i.e. violation of God's right), there is disagreement among the scholars on whether or not such a confession amounts to criminal defamation. According to a first view held by the majority of scholars, including the Hanafis, Ma̅likis, a group of Shafi‘is and Hanbali's, it is preferable that such a person does not confess the crime nor expose himself. This view is based on several hadiths of the same purport, including the one reported on the authority of Abu Hurairah who said: “Ma̅‘iz Ibn Ma̅lik came to the Prophet and said: 'I have committed fornication,' and he (the Prophet) turned away from him. He said: 'I have committed fornication,' and he turned away from him. Then, he said: I have committed fornication, and he turned away from him, until when he had confessed four times, he ordered that he should be stoned." Since the Prophet turned away from the man who came to confess a violation of God's right (i.e. fornication), it has been inferred that concealing a sin of this kind is more preferable.
The second view of the preference of confessing the crime constituting a violation of God's right is upheld by some Sha̅fi‘i scholars as well as the Ẓa̅hiris. This view is based on the report that after carrying out the fornication penalty against Ma̅‘iz, the Prophet said, "Ask forgiveness for Ma̅‘iz b. Ma̅lik. So, people said 'May Allah forgive Ma̅‘iz b. Ma̅lik.' Thereupon Allah's Messenger said: He (Ma̅‘iz) has made such a repentance that if that were to be divided among a people, it would have been enough for all of them." Since the Prophet lauded the repentance of Ma̅‘iz as mentioned in this hadith, it has been inferred that confession of illegal acts is more preferable.
However, the above view may be rejected on the basis that the Prophet lauded Ma̅‘iz' repentance only after he had made the confession and after the penalty had been carried out, and that the repentance and purification of his sin that merited that praise by the Prophet were dependent and conditional on the execution of the penalty, and hence it may be said the first view has more sound bases.
Fourth, one defaming another person. As explained above, it is prohibited for a Muslim to defame himself. So, for a greater reason, by analogy, this applies to one defaming another person.
Fifth, one defaming another person while lying. Being an abominable behavior to defame another person via a false statement, Allah promised those who engage in this sort of defamation a severe punishment in this world and the next, declaring, "There is painful punishment in this world and the next for those who like that immorality (faḥishah) should spread among the believers." Faḥishah here means fornication or immoral speech, which of course includes false rumors. Allah even cursed those who engage in slander (Qadhf), being a form of speech that is technically subsumed under defamation, saying, "Verily those who blaspheme unsuspecting chaste believing women will be cursed in this world and the next; and for them there will be severe punishment."
Sixth, defaming another person while telling the truth. Defaming a person while telling the truth is also prohibited for it is considered as ghi̅bah, and the prohibition of ghi̅bah is well-established in the Sharia. However, there are exceptions where speaking ill of a person truthfully does not constitute abominable defamation, and these include, inter alia, defaming the oppressor by the oppressed person, seeking fatwa, impugning the witnesses etc. These exceptions are also tackled in detail above under the section of the cases of permitting ghi̅bah. Added to these cases is defamation that is done as a part of the disciplinary punishment of ta‘zi̅r. A great number of scholars spoke of the permissibility of punishing a convicted criminal with defamation if the judge sees it appropriate to do so. For example, Ibn Farḥu̅n states: "If a judge sees a good reason for deterring the criminals by defaming them, he may do so." Al-Ma̅wardi also holds a similar view as that of Ibn Farḥu̅n.
The only case in which defamation may be penalized with a fixed penalty (ḥadd) is when defamation is tantamount to slanderous accusation (Qadhf). In the other cases where defamation is of a lesser degree, the offence may be penalized under ta‘zi̅r.
As explained above, defamation may take several forms, including one defaming one's self whether by lying or telling the truth, or one defaming another person whether by lying or telling the truth. It is shown that all these forms of defamation, based on evidence, are prohibited, except for a limited number of cases where defamation may serve a moral purpose or where it is not intended per se.
It may be said this prohibition of this form of expression and the severe punishment it merits in most cases conform to the collective Sharia objective of protecting people's honor and reputation from hurtful statements and false rumors. If this position was not upheld by the Sharia, the honors of people would be left vulnerable, which results in a greater social corruption.
 Ibn Manẓu̅r, Lisān Al-‘Arab, vol. 4, 432.
 Muḥammad As-Sarkhasi, Al-Mabsu̅t ̣(Beirut: Da̅r Al-Ma‘rifah, 1993), vol. 4, 102.
 Ibn Kathi̅r, Tafsi̅r Al-Qur'a̅n Al-‘Aẓi̅m, vol. 6, 29.
 Al-Bukha̅ri, Ṣaḥi̅ḥ Al-Bukha̅ri, vol. 8, hadith no. 6066, 19.
 Ibn Ḥajar, Fatḥ Al-Ba̅ri, vol. 10, 482.
 Al-Bukha̅ri, Ṣaḥi̅ḥ Al-Bukha̅ri, vol. 8, hadith no. 6499, 104.
 Ibn Ḥajar, Fatḥ Al-Ba̅ri, vol. 11, 337.
 See Shams Ad-Di̅n Ash-Sherbi̅ni Ash-Sha̅fe‘i, Mughni Al-Muḥta̅j ila M‘arefat Ma‘a̅ny AlFa̅ẓ Al-Menha̅j (Beirut: Dar Al-Kutub Al-‘Elmyyah, 1994), vol. 6, 386.
 See Kama̅l Ad-Di̅n Ibn Hama̅m, Fatḥ Al-Qadi̅r (Cairo: Da̅r Al-Fikr, n.d.), vol. 5, 280.
 See Bahra̅m Ad-Demi̅ri Ad-Demia̅ty, Ash-Sha̅mel fi Fiqh Al-Ima̅m Ma̅lik (Casablanca: Markaz Najebawi̅h lel-Makhṭu̅ṭa̅t wa Khedmat At-Tura̅th, 2008), vol. 2, 854.
 See Shams Ad-Di̅n Ash-Sha̅fe‘i, Mughni Al-Muḥta̅j, vol. 6, 386.
 See Ibrahi̅m Ibn Mufleḥ, Al-Mubde‘ fi Sharḥ Al-Muqne‘ (Beirut: Da̅r Al-Kutub Al-‘Elmyyah, 1997), vol. 7, 463.
 Al-Bukha̅ri, Ṣaḥi̅ḥ Al-Bukha̅ri, vol. 8, hadith no. 6815, 165.
 See Abu Al-Ḥassan Al-Ma̅werdi, Al-Ḥa̅wi Al-Kabi̅r, ed. ‘Ali Muḥammad Mu‘awwaḍ and ‘A̅del Abdul-Mawju̅d (Beirut: Da̅r Al-Kutub Al-‘Elmyyah, 1999), vol. 13, 202.
 Abu Mụhammad Al-Qurṭubi Aẓ-Ẓaheri, Al-Muḥalla bil Ạtha̅r (Beirut: Da̅r Al-Fikr, n.d.), vol. 12, 50.
 Muslim, Ṣaḥi̅ḥ Muslim, vol. 3, hadith no. 1695, 1321.
 Muḥammad Ash-Shawka̅ni, Fatḥ Al-Qadi̅r (Damascus: Da̅r Ibn Kathi̅r, 1414 A.H.), vol. 4, 17.
 Ibrahi̅m Ibn Farḥu̅n, Tabṣi̅r Al-Ḥukka̅m fi Usu̅l Al-‘Uqdiah wa Mana̅hej Al-Aḥka̅m (Cairo: Maktabat Al-Kullya̅t Al-Azharyyah, 1st edition, 1986), vol. 2, 150.
 See Abu Al-Ḥassan Al-Ma̅wardi, Al-Aḥka̅m Al-Ṣulṭanyyah (Cairo: Da̅r Al-Hadi̅th, n.d.), 324.