Allahumma l-'an qatalata Amir al-Mu'minin

The phrase Allāhumma l-ʿan qatalata Amīr al-Muʾminīn (Arabic: اللّهم الْعَنْ قَتَلَةَ اَمیرِالمُؤمنین) meaning "O Allah, curse the killers of Imam Ali" is used in some of the ziyara texts of Imam Ali (a). Shaykh Abbas Qummi mentioned that reciting it a hundred times is part of the recommended acts for the night of the 19th of Ramadan.

According to Ayatullah Khamene'i, the use of the plural form "قتلة" (killers) indicates that it refers not only to Ibn Muljam, who struck Imam Ali (a) with a sword, but also includes those who played a role in causing this event. This includes those who compelled him to accept arbitration during the incident of Hakamiyya and others who, through their actions, contributed to his martyrdom.

Muhsin Qara'ati, a Shia cleric and commentator, also interpreted the term "قتلة" to refer to the movement, ideology, and group that Ibn Muljam represented. He further stated that the term is used to include those who were complicit in the assassination of Imam Ali (a), even those who were satisfied with it.

Based on a jurisprudential response from Mirza Jawad Tabrizi, there is no issue with reciting this supplication during qunut or in prostration during prayer.