There are many references to the death penalty for blasphemy. Here is an excellent SAHIH hadith in which Muhammad approves of a man killing the mother of his children for making fun of Muhammad. Thanks to David Wood for this:
Sunan Abu Dawud 4361 (Muhammad on Killing Critics of Islam)
Here’s Sunan Abu Dawud 4361 (4348 in some editions), in English and Arabic, along with the rating (sahih). In this hadith, a man kills the mother of his children for speaking against Muhammad. Muhammad, in response, says that no one is to punish the man.
So when Muhammad’s own companions killed critics of Islam, and Muhammad approved, why do politicians, the media, and Muslim groups keep insisting that killing critics has nothing to do with Islam?