27 June sees the anniversary of the martyrdom of Imam Ali (a.s.) and Muslims celebrate this day together in remembrance of him. On the day of his assassination he went to the mosque in Kufah for the morning prayers, but that morning he requested that his two sons remain at home. They usually accompanied their father, but on that day, he insisted that they stay behind. Upon arrival at the mosque, he did the morning call to prayer and then led the congregation.
The assassinator was a man named Abdurrahman Ibn Moljem, who was present that morning. He pretended to take part in the prayers that morning and stood behind Imam Ali (a.s.). While they were in prayer, he stood up and drew a "poisonous sword," striking Ali (a.s.)on the back of the head.
Although mortally wounded, Ali (a.s.) was still conscious at that point, and they brought his assassinator before him. His hands had been tied with a rope which was cutting into his flesh. When Ali (a.s.) saw this, he felt for the man and insisted that he be untied, even though he was wounded and in pain too. The man started weeping when he saw this.
His assassinator was to be put to death for his actions. Ali (a.s.), however, made sure that his murderer would in no way be tortured before the execution, and that he only be killed with a "blow of a sword." Ali also requested that the body of his murderer not be mutilated in any way and that his relatives were not to come under any harm either.
Ali (a.s.) was taken home where he laid and was able to speak softly with his two sons and make his requests for the day of his funeral, before his death. While he was speaking to them, he asked that they bury him at a secret location, so as to ensure that his enemies did not desecrate his burial place. Ali passed away and his sons followed his wishes, just as he had asked.
The day Imam Ali (a.s.) was assassinated remains a "cruel, brutal and hideous "crime as it was seen as not just a crime against a single person, but against the whole Islamic leadership. This act was considered to be an attack against the message which Imam Ali (a.s.) brought, as well as the history and culture of the Muslim people on that day.