Three names recur whenever critics argue that Muhammad silenced his opponents by force: Kaʿb ibn al-Ashraf, Asmāʾ bint Marwān and Abū ʿAfak. All three are described as poets, and all three are said to have been killed at the Prophet’s instruction for verses against him. The conclusion drawn is that critics killed on his order prove that Islam punishes criticism with death. The three cases do not stand on the same evidence, and they do not describe the same thing. Treating them as one story hides both facts.

Two questions that must be kept apart
The first question is historical: did the event happen as reported? Islamic scholarship has its own discipline for answering that, based on the reliability of each chain of narrators, and it applies the discipline to reports that favour the Prophet as strictly as to those that embarrass him. The second question is moral and legal: if the event happened, what was the person killed for? An answer to the first question settles nothing about the second, and an argument that skips from “he was killed” to “he was killed for criticism” has skipped the step that matters.
Asmāʾ bint Marwān and Abū ʿAfak
The stories of Asmāʾ, a woman said to have been killed at night for verses mocking the Muslims, and Abū ʿAfak, an elderly man said to have been killed for similar verses, are the most emotive of the three. They are also the weakest. Neither appears in Ṣaḥīḥ al-Bukhārī, Ṣaḥīḥ Muslim or any of the six canonical collections. They come from the biographical literature, chiefly Ibn Isḥāq’s biography of the Prophet and the compilation of Ibn Saʿd, whose chain runs through al-Wāqidī, a historian whom the hadith critics rejected as a transmitter.
The version with a full chain fares worse. Ibn ʿAdī recorded it in his catalogue of weak narrators through Muḥammad ibn al-Ḥajjāj al-Lakhmī and noted that the narrators accused this man of forging it. Ibn al-Jawzī listed the report among fabrications, and in the modern period al-Albānī classed it as fabricated (mawḍūʿ). Al-Bukhārī said of Muḥammad ibn al-Ḥajjāj that his narrations are to be rejected. By the standards Muslim scholars apply to every report, these two stories do not establish that the events took place.
Critics sometimes respond that Muslims discard reports only when they are inconvenient. The charge has force only if the standard is applied selectively. Here it is applied consistently: the same scholars who reject the Asmāʾ report also reject fabricated reports praising the Prophet, and the narrators involved were judged weak in every subject they transmitted, not merely in this one.

Kaʿb ibn al-Ashraf
Kaʿb’s case is different, because it is reported in the most authoritative collections. Ṣaḥīḥ al-Bukhārī preserves it through Jābir ibn ʿAbd Allāh:
Muḥammad ibn Maslamah volunteered, and Kaʿb was killed. Any honest account has to accept that this happened and that it happened at the Prophet’s instruction. The question is what “harmed God and His Messenger” refers to, and here the biographical sources fill in the context that the hadith compresses.
Kaʿb was a leader of the Banū al-Naḍīr, one of the Jewish tribes of Medina bound to the Muslims by the covenant that governed the city. After the Battle of Badr in 624, according to the early biographers, he travelled to Mecca, mourned the Quraysh dead in verse and urged the Quraysh to take revenge on the Muslims. He returned to Medina and composed verses about Muslim women. The Quraysh were at war with Medina, and within a year they would march on it at Uḥud.
A treaty-bound member of a city’s alliance who travels to the enemy’s capital in wartime and urges it to attack the city is doing something that every legal tradition, ancient and modern, treats as treason. Poetry was the propaganda of Arabia, the medium through which tribes rallied for war; Kaʿb’s verses were part of a campaign of incitement, and that campaign was directed at people who would shortly be killed in battle. One may still judge the method harsh. That is a fair moral discussion. It is a different discussion from the claim that the Prophet killed people for disagreeing with him.

What the Quran says about mockery
The Quran addresses mockery of the believers and of their faith directly, and its instruction is patience:
The verse anticipates exactly what the critics describe, hurtful speech from opponents, and its command is endurance and God-consciousness. Elsewhere it tells believers what to do when they hear the verses of God ridiculed:
The instruction is to leave the gathering until the conversation turns to something else. The Prophet lived for years in Mecca among people who mocked him openly, and the sources record no attempt to have any of them killed. When he entered Mecca as its ruler in 630, he pardoned the great majority of those who had fought and ridiculed him for two decades.
What the evidence supports
Set out case by case, the record looks like this. Two of the three famous stories rest on chains that Muslim hadith criticism itself judges fabricated, and they cannot bear the weight placed on them. The third is authentic, and on the account of the early sources it concerns a treaty ally who incited an enemy at war against the city he was bound to protect. None of the three shows a policy of killing people for criticism, and the Quran’s own instruction about mockery points the other way.
Modern discussions of apostasy-and-freedom/" class="ce-crosslink" title="Why Can’t People Leave Islam Without Consequences?">blasphemy law in Muslim societies deserve serious attention in their own right, and some of what is done today in the name of honouring the Prophet bears little resemblance to his conduct. That debate is better served by an accurate account of what happened in Medina than by a list of names stripped of their sources and their circumstances.