Imam Ali (A.s)
On the 19th of the month of Holy Ramadan (Mah e Ramzan) of the year 40 A.H, Imam Ali (pbuh) came to the mosque in Kufa for his morning prayers. Imam Ali (pbuh) gave the call for prayer (Azaan) and became engaged in leading the congregation. Abd-al-Rahman ibn Muljam pretending to pray, stood just behind Imam Ali (pbuh), and when Imam Ali (pbuh) was in a state of prostration, Abd-al-Rahman ibn Muljam dealt a heavy stroke with his sword, inflicting a deep wound on Imam Ali's (pbuh) head.
This was the time when Imam Ali (as) uttered his famous words : "Fuzto warab-il-Kaaba" - "By the Rab of Kaaba, I am successful".