Is it obligatory to kill one who reviles the Prophet after he has repented, and must he surrender himself to the authorities? And is saying that the beard is filth or a sign of self-neglect an act of disbelief or a sin if one does not intend to mock the religion?

The repentance of one who curses is acceptable between him and Allah, according to the preponderant view, due to the generality of the verses concerning repentance. The Hanafis, Hanbalis, and Shafi'is held that his repentance is accepted. The Hanafis, Hanbalis, and Ibn Taymiyyah held that one who curses the Prophet, peace and blessings of Allah be upon him, is considered an apostate, so he is asked to repent, and his repentance is accepted. Sheikh Ibn Baz and Sheikh Ibn Uthaymeen preferred the view that the repentance of one who curses the Prophet, peace and blessings of Allah be upon him, is accepted. He is not obligated to go to the authorities for the Hadd punishment to be carried out; rather, he is obligated to repent, conceal himself, and increase in righteous deeds.