Islamic Studies
Caliphate & Rulers: From the Rightly Guided Caliphs to the Ottoman Caliphate
Explanation
Ali (RA) was assassinated by Abdur-Rahman ibn Muljam, a Kharijite, who struck him with a poisoned sword while he was leading the Fajr prayer on 17th (or 19th) Ramadan 40 AH.
Reference: Islamic Studies - Caliphate & Rulers
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