It is also obligatory to report him to the authorities who can carry out the punishment on him. . If there is no one who can carry out the hadd punishment of Allaah and stand up for the Messenger (peace and blessings of Allaah be upon him) then the Muslim has to do whatever he can, so long as that will not lead to further mischief and harm against other people. But if a Muslim hears a kaafir defaming the Prophet (peace and blessings of Allaah be upon him) and he keeps quiet and does not respond for fear that this person may then defame him even more, this is mistaken thinking
Shaykh ‘Abd al-Rahmaan al-Barraak, Majallat al-Da’wah, Muharram, issue no. 1933.
http://www.islamqa.com/en/ref/14305/defamation of the prophet
In the case of defamation, the hadith says:
“If you find him alive – although I do not think that you will find him alive – then strike his neck (kill him). And if you find him dead then burn him with fire.” He said: This is what the Messenger of Allaah (peace and blessings of Allaah be upon him) said concerning “one who tells lies about me deliberately.” Shaykh al-Islam said: “This is a saheeh isnaad according to the conditions of al-Saheeh and we do not find any fault in it.” Then he said: There are two opinions concerning this hadeeth:
Islam QA says about this hadith
There are two opinions concerning this hadeeth:
1 – That the apparent meaning should be followed and the one who deliberately tells lies about the Messenger of Allaah (peace and blessings of Allaah be upon him) should be killed
........Their is also a second opinion
2 – The liar is to be punished severely, but he is not regarded as a kaafir and it is not permissible to kill him, because the factors that determine who is a kaafir and is to be killed are well known and this is not one of them. It is not permissible to affirm something for which there is no basis. Whoever says that he is not to be executed has to stipulate that telling lies about the Prophet (peace and blessings of Allaah be upon him) does not imply any criticism or defamation of him.
But if he says that he heard him say something that implies belittling the Prophet (peace and blessings of Allaah be upon him) or criticizing him, such as the hadeeth about “the sweat of horses” and other such silly fabrications, this is obviously mocking him, and the one who says this is undoubtedly a kaafir whose blood may be shed. Those who were of the view that such a person is not to be executed responded to this hadeeth by saying that the Prophet (peace and blessings of Allaah be upon him) knew that he was a hypocrite so he killed him for that and not for lying, but this answer does not count for anything.
The hadith is clear on what should happen to somone who lies about the prophet to defame him
http://www.islamqa.com/en/ref/34725/defamation of the prophet
http://islam.worldofislam.info/inde...ngs-of-allaah-be-upon-him&catid=130&Itemid=44
Finally, in this day and age, even islamic governments and non-muslim authorities do not even implement the punishment of allah.
If a muslim can not find an "Imam" or "Ruler" to implement his punishment.....well heres the story of an apostate called "Farag Foda" who used to mock the prophet.
An Al-Azhar University scholar, Mohammed al-Ghazali, a witness before the court, declared it was not wrong to kill a foe of Islam. Al-Ghazali said:
"The killing of Farag Foda was in fact the implementation of the punishment against an apostate which the imam (the Islamic leader) has failed to implement (undertake)."
also see
Shaykh ‘Abd al-Rahmaan al-Barraak, Majallat al-Da’wah, Muharram, issue no. 1933.[/QUOTE]
More info: http://www.sunniforum.com/forum/sho...t-executing-quot-somone-who-mocks-the-prophet