Allah Almighty says: {Indeed, Allah’s curse is upon the wrongdoers.} [Surat Hūd: 18] Allah Almighty also says: {Then a caller will announce among them, “May Allah’s curse be upon the wrongdoers.”} [Surat al-A‘rāf: 44]
It is authentically narrated that the Messenger of Allah (may Allah’s peace and blessings be upon him) said: “May Allah curse the woman who joins false hair to real hair [extensions] and the one who asks for it to be done to her.” He also said: “May Allah curse the consumer of Riba.” And he invoked Allah’s curse on those who produce images, and those who change land boundary markers. And he said: “May Allah curse a thief, (even the one) who steals an egg,” and said: “May Allah curse him who curses his parents,” and “May Allah curse the one who slaughters for other than Allah,” and: “If anyone commits a crime in it (Madinah) or gives shelter to a criminal, he is cursed by Allah, His angels, and all the people,” and said: “O Allah! Send your curse upon Ri‘l and Dhakwān and ‘Usayyah, as they disobeyed Allah and His Messenger.” Those were three Arabian tribes. He also said: “May Allah curse the Jews; they took the graves of their prophets as places of worship,” and said: “May Allah curse those men who assume a feminine attitude, and those women who assume a masculine attitude.”
All these wordings are mentioned in the books of authentic Hadīths, some of them are cited in Sahīh Al-Bukhāri and Sahīh Muslim, and others are cited in one of them only. I referred to only some of them for the sake of brevity, but I will list most of them in the relevant chapters of this book, Allah willing!
1) It is impermissible to invoke Allah’s curse on a specific individual, except when there are reported Shariah texts about cursing that person in particular. As for generalization, it is permissible to invoke Allah’s curse on those who deserve to be cursed like the wrongdoers for example.
2) Cursing means expulsion from the mercy of Allah Almighty.