The Prophet ʿAlī ibn Abī Ṭālib was killed while praying.
ʿAlī, the fourth caliph of Islam and a central figure in Shia Islam, was assassinated by a Khārijite while leading prayers in the mosque of Kufa in 661 CE (19th of Ramadan). A Khārijite struck him with a poisoned sword, leading to his death. The assassins targeted ʿAlī, Muʿāwiyah, and ʿAmr ibn al-ʿĀs, but only ʿAlī was successfully attacked.
