Some people curse one another even if the other person is not deserving of the curse. A believer must always remember that cursing is not the attribute of a Muslim who wants to attain perfect faith.
It was narrated by Imam Ahmad in his Musnad and Imam al-Tirmidhi in his Jaami’ from ‘Alqamah that ‘Abd-Allaah ibn Mas’ood (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “The believer is not a slanderer, one who curses a great deal, one who indulges in obscenity or who in engages in foul talk.” Al-Tirmidhi said: It is a hasan ghareeb hadeeth. And it was narrated in al-Saheehaynfrom Thaabit ibn al-Dahhaak that the Prophet (peace and blessings of Allaah be upon him) said: “Cursing a believer is like killing him.”
Based on this hadith it is not permissible for a Muslim to curse his fellow Muslim brothers and sisters except those whom Allah has cursed in His glorious Book.
For a Muslim, it is not permissible to curse one who has committed or who commits a sin because of his/her sin such as a person consuming usury. Rather it is a duty of the Muslim to advise the person and encourage them to observe the rulings of Islam. Advice must be given in kind and gentle methods.
If anyone curses someone who does not deserve to be cursed, there is a stern warning that the curse will come back on the one who utters it if it is not justified. This is indicated by the report narrated by Abu’l-Darda’ (may Allaah be pleased with him) who said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “When a person curses something, the curse ascends to heaven, and the gates of heaven are closed to it. Then it comes back down to earth and the gates of the earth are closed to it. Then it looks right and left, and if it does not find anywhere to go, it goes to the one who was cursed, and if he deserves it (it befalls him), otherwise it goes back to the one who uttered it.” Narrated by Abu Dawood in his Sunan.
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions.