On July 7, 2011, Egyptian Shaykh Abu-Ishaq al-Huwayni (who we've heard from before) appeared on the Egyptian satellite television station al-Hikma. In this startling interview, Al-Huwayni contends that anyone who insults the prophet Muhammad, even if he or she later repents, must be put to death. According to Translating Jihad:
Later in the interview, al-Huwayni goes on to contrast this with the case of one who insults Allah. He says that insulting Allah of course makes one an infidel, which is agreed to by all Islamic scholars, yet the one who insults Allah is not killed--he is merely called to repentance. This is because even if the whole world insults Allah, it does not matter to him--it does not hurt him.
Below, find a small portion of this interview, complete with translated subtitles:
Here is the translated text of al-Huwayni's statement, courtesy of Translating Jihad:
Whoever insults the Prophet (PBUH), if he later comes and apologizes, and kisses the shoes (of the ruler), and says, “I want all Muslims, every one, to return and strike me with the soles of their feet”—does the ruler have the right to accept this?
I bring up this question, as it was asked of me. The answer is that it is not permissible for anyone to accept this. Then what do we do with him? We kill him! But he told you that he repented. We still kill him, even if he repents!