I was disturbed to see that Hizb al-tahrir -- a group well-known for its eccentric positions on the Khilafa -- issued a statement claiming that Islam supports the concept of "honor" killing based on a dubious analogy to the fact that someone killed protecting his honor is deemed a martyr. I wish I could have appended my response to their "communique," but it was so shockingly reflective of ignorance that my only choice was to delete it immediately and ask Allah to guide us out of the ocean of darkness in which we find ourselves.
Meanwhile, having found a few minutes, I located Ibn 'Abd al-Barr's discussion of this issue in his monumental "Al-Istidhkar li-madhahib fuqaha` al-amsar," which is a book of comparative fiqh in the guise of a commentary upon the Muwatta` of Imam Malik, may Allah be well-pleased with him.
Malik narrates in a chapter titled "The Legal Ruling (qada`) Regarding One Who Finds a [non-Mahrim] Man With His Wife," on the authority of Abu Hurayra that Sa'd b. 'Ubada, said to the Prophet (S) "Suppose I find a man with my wife. Should I leave him [with her] until I bring four witnesses?" The Prophet (S) said, "Yes."
Ibn 'Abd al-Barr said: "This hadith includes the following legal principles: the prohibition against applying a legal penalty without legal authority (sultan) and without witnesses in order to prevent the means to shedding the blood of a Muslim based merely upon the claim of his accuser, the one seeking the shedding of the accused's blood. [In this case] the truth of the claim would be known only by [the accuser's] own statement and Allah, may He be glorified and sanctified, has made the life of a Muslim a precious thing, and has made the sin in taking it great as well. Therefore, it [legal punishment] is permissible only under the conditions in which Allah has permitted it. Applying legal punishments is exclusively for the government so that it may apply that which Allah has commanded in His book or on the tongue of His Prophet (S)."
Malik also narrated on the authority of Sa'id b. Yahya from Sa'id b. al-Musayyib that "A man from Syria, with the name of Ibn Khaybari, found a man with his wife so he killed him, or both of them. Mu'awiya b. Abi Sufyan was unsure of how to rule in his case so he wrote a letter to Abu Musa al-Ash'ari, asking him to ask 'Ali b. Abi Talib [about this case]. So he asked 'Ali about that case, and 'Ali told him, 'This is not a case in my domain. I beseech you to tell me [its circumstances].' Abu Musa al-Ash'ari told him that Mu'awiya b. Abi Sufyan had written him a letter directing me to ask you this question. Ali said, 'I am Abu Hasan -- if he [Ibn Khaybari] does not produce four witnesses, let him be given with a rope [to the relatives of the deceased] (fa-l-yu'ta bi-rummatihi)."
This report was also reported by Ibn Jurayj, Ma'mar, al-Thawri, all on the authority of Yahya b. Sa'id from Sai'd b. al-Musayyib.
Ibn 'Abd al-Barr said: "It means that he [the judge/ruler] should deliver him [the killer] with a rope around his neck to the relatives of the victim so that they may take qisas against him. It was also said that he [the judge/ruler] should deliver him [the killer] with a rope around his neck to the relatives of the victim so that they may take qisas against him unless he produces four witnesses to an act of adultery whose obligatory punishment is stoning."
. . .
The bulk of jurists in the townships, the people of opinion and the people of transmitted knowledge concur in Ali's opinion, bountiful praise to Allah.
'Abd al-Razzaq also transmitted on the authority of Ma'mar from al-Zuhri, who said: A man asked the Prophet (S), saying 'A man finds another man with his wife; shall he kill him?' The Prophet (S) said, "No, not without proof."
Abu Bakr b. Abi Shayba said "'Abda b. 'Asim told me on the authority of al-Hasan, that he said, 'Punishments [al-hudud] are [the responsibility] of the government [al-sultan]."
This [opinion] is attributed to Ibn Muhayriz, 'Ata` al-Khurasani, and 'Umar b. 'Abd al-'Aziz, and there is no disagreement on this point.