Is there a consensus on not accepting the repentance of one who insults the Prophet (peace be upon him), and is one who utters a word of insult, intending to insult, upon seeing the name of the Prophet (peace be upon him) without mentioning his name, considered an insulter, and is this sin forgivable through repentance?

Slandering the Prophet, peace and blessings be upon him, is an act of disbelief (kufr) and apostasy (riddah) that necessitates execution, by consensus. As for the repentance of the slanderer, it is accepted between him and Allah the Almighty, by consensus. However, there is a difference of opinion regarding the acceptance of his repentance in this world such that he is not killed. Some scholars, among them Sheikh Abu Bakr al-Farsi, are of the view that he must be executed even if he repents, and they claimed consensus on this, arguing that the Hadd (prescribed punishment) for slandering the Messenger is like other Hudud and is not negated by repentance. Others, however, such as Abu Hanifa, Al-Thawri, and Malik in one narration, believe that his repentance is accepted in this world as well. Qadi Iyad indicated that the well-known position of Malik's madhhab (definition) and the majority of scholars is that he is to be killed as a Hadd (punishment), not for disbelief, if he outwardly repents. Thus, his repentance is not accepted in dropping the Hadd from him, but his repentance benefits him between him and Allah. Whoever slanders the name of the Prophet, peace and blessings be upon him, or anything that signifies him, with the intention of slandering, is a disbeliever and an apostate, and his repentance is accepted between him and Allah the Almighty, because Allah forgives all sins for whoever repents.