Repentance from cursing believer
23-5-2017 | IslamWeb
Question:
Assalaamu alaykum. On your website, it says that one of the sins that Allaah may not forgive even if one repents is killing a believer. Please see: https://www.islamweb.net/en/fatwa/87847. You also said that the majority believe that there is complete repentance for killing a believer but that a minority of scholars nevertheless believe that Allaah will not forgive the believer's killer. If we take the opinion of the minority of the scholars, given that they could be right, then what about the hadith that says, “Cursing a believer is like killing him, and accusing a believer of Kufr (disbelief) is like killing him”? I have cursed many believers and even may have made Takfeer (declaring a Muslim to be a disbeliever) on one or two, am I counted as having killed them? Is there no path to redemption; am I doomed according to the opinion of the minority of the scholars? I am Muslim by the way. Please help me with references to the Quran and Sunnah. May Allaah reward you all immensely.
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
First of all, you should know that the view of the majority of the scholars about the mentioned issue is the most preponderant view, and the other view is less preponderant (outweighed).
Under any estimation, what you mentioned about the matter of cursing or Takfeer has no relation to what is mentioned here. Rather, what is meant is resembling it with killing in regard to the prohibition or the punishment, as has been stated by the scholars.
The book Tuhfatul-Ahwathi, when speaking about the interpretation of the hadeeth, reads:
“Cursing a Muslim is like killing him: At-Teebi 
said, ‘It means like killing him in prohibition or punishment (of killing),’ ‘and accusing a believer of Kufr is like killing him’, he (At-Teebi) said, ‘It most likely means resemblance, as it refers to the Kufr that necessitates killing the person accused of Kufr, and he (the accuser) is the one who caused this accusation of Kufr and thus the killing of the Kaafir (disbeliever), and the one who causes something is like the one who executes it…’”
However, resembling something to something else does not necessarily mean that it is equal to it in every aspect.
The Muslim must beware of cursing or Takfeer, and if someone does this without insight, meaning without taking the Shariah criteria in this regard into account, then he is in grave danger. Indeed, a believer is neither a slanderer nor a curser, nor is he obscene or vulgar, as has been reported in the authentic Sunnah.
For more benefit, please refer to fatwas 8106 and 87963.
Allah knows best.