In 40 H after the Battle of Nahrawan the remnants of Khawarij had a conclave in Makkah and discussing about the loss of lives in their ranks, they put the blame of these killings on `Ali (a.s), Mu`awiyah and `Amr Ibn al-`As. To avenge all those killings, they wanted to do away with all the three. The blood of the Khawarij was already seeking revenge. They unanimously agreed that Bakr ibn `Abdullah al-Sarimi would kill Mu`awiyah, `Amr ibn Barrak al-Tamimi to kill `Amr ibn al-`As and `Abd al-Rahman ibn Muljim to assassinate `Ali (a.s). They also agreed that all the three killings were to be committed on the same day and at the same time. They did not want any of the three to get the wind of the killing of the other and get wary and make the attempts fail. Therefore, they fixed the day and time and sent Barrak ibn `Abdullah to Damascus, `Amr ibn Bakr to Egypt and `Abd al-Rahman ibn Muljim to al-Kūfah.
For this difficult task they had fixed 19th of Ramadan and the time was the Morning Prayer. Therefore, Barrak ibn `Abdullah reached the Masjid of Damascus and when the congregation stood up, he took station behind Mu`awiyah in the first row. When Mu`awiyah bent forward in genuflection, he struck a blow with his sword. The wound was small and healed within a few days. The assailant was taken captive. `Amr ibn Bakr reached the Masjid of Egypt on the night of 19th Ramadan with the plan of killing `Amr ibn al-`As during the Morning Prayer, but it so happened that `Amr ibn al-`As suffered from a bout of colic and had deputed Kharijah ibn Hudhafah al-Sahmi to lead the prayer in his place. `Amr ibn Bakr was not able to identify in the darkness that it was not `Amr ibn al-`As. He killed Kharijah in that confusion. The people caught hold of him, bound him in ropes and took to `Amr ibn al-`As. When he realized that Kharijah was killed by him in place of `Amr ibn al-`As, he felt sorry for the failure of his design. `Amr ibn al-`As addressed him and said, “You wanted to kill me, but the death turned towards Kharijah and you have failed in your attempt on my life!” Then he was killed for killing Kharijah.
`Abd al-Rahman ibn Muljim arrived in al-Kūfah around the end of the month of Sha`ban and stayed in the locality of Banū-Kindah with some Khawarij. He did not inform anyone of his plans nor did he give any indication of his intention through his behavior. In that time he developed acquaintance with a Khariji woman, Qatam bint Taymiyah. He fell for her at the first sight. When he knew that she was a spinster, he proposed marriage to her. Qatam’s father and brother were killed in the battle of Nahrawan and she wanted to wreak vengeance on `Ali (a.s). But she did not find any way to fulfill her wish. When Ibn Muljim proposed to her, she saw a ray of hope in the proposal. Therefore, she said, “I am willing to marry you but my dowry is 3,000 dirhams, a male slave, a slave girl and the killing of `Ali ibn Abi-Talib.”
Ibn Muljim was already having plans for that crime, he had come there for that purpose and now another strong motive presented itself to make him more determined for the act. But outwardly he expressed surprise at the suggestion and he said, “Killing `Ali is not an easy task!”
Qatam said, “You can make a surprise attack and kill him. If you succeed, it is well and good. Even otherwise you will get the Blessings of the Hereafter!” When Ibn Muljim saw that Qatam had the same feelings as himself, he told her that he had come to al-Kūfah with the same purpose and wanted to avenge the deaths of his men in the battle of Nahrawan. Then Qatam told him that he must act with determination and she would talk to dependable persons of her tribe to extend their cooperation. Therefore, she prepared Dardan ibn Mujalid to assist him. Ibn Muljim took Shabib ibn Bajrah al-Ashja`i and al-Ash`ath ibn Qays into confidence and kept waiting for the day and time of the act.
During that month of Ramadan, `Ali (a.s) was alternately going to the houses of his children and that of `Abdullah ibn Ja`far to break his fasts. His appetite had gone down very much and he used to take only a few morsels of food. When asked about it, he would say:
“I wish that when my death comes, I should be on an empty stomach!”
On the night of 19th Ramadan, the Imam (a.s) went to her daughter Ummu-Kulthūm’s house. She offered him two breads of barley, a bowl of milk and some salt. When he saw the food he said, “In following the foot steps of the Prophet (a.s) I have never had more than one type of food on my spread. O Daughter! There is accountability for the legitimate and retribution for the
 Al-Kāmil fit-Tārīkh, Vol 3, Page 195
illegitimate. Do you want your father to stay longer at the station of accountability of the Day of Judgment? Remove one of the two things from the spread!”
Ummu-Kulthūm took away the bowl of milk and Amir al-Mu’minin (a.s) ate a few morsels of the bread with the salt. After the meal, according to his practice, he stood up on the mat to offer his prayer. But he was looking up repeatedly at the twinkling stars and said:
“By Allah! I am not lying nor am I making a wrong statement! This is the night about which promise has been made to me!”
In uneasiness he sometimes recited Sūrah Yasin, sometimes he said “We are Allah’s and to Him do we return,” and sometimes “There is neither might nor power save with Allah, the Most High, the All-great,” and “O Allah! Make death felicitous for me!” When Ummu-Kulthūm saw this, she asked, “Father! Why are you so worried today?” He replied, “I have the Hereafter in front of me! I am going to the Presence of Allah!” Tears welled in the eyes of Ummu-Kulthūm and she said, “Father! Today you should not go to the Mosque! Ju`dah ibn Hubayrah is there. Ask him to lead the prayer!” The Imam (a.s) said, “There is no escape from the Fate fixed by Allah” The night was in its last stages when the Muezzin, Ibn tabaj came and informed about the prayer. The Imam (a.s) rose to move towards the mosque.
When he came to the courtyard of the house, the domesticated geese started shouting and swaying their wings. Someone wanted to move them aside, but the Imam (a.s) said, “Leave them alone! After a short time the sounds of crying and wailing would start” Imam al-Hasan (a.s) or Ummu-Kulthūm said, “Father! What sort of things you are saying today!” He said, “This is the truth that has come out of my mouth!” Then the Imam (a.s) told Ummu-Kulthūm, “My daughter! These birds cannot speak! Take care of feeding them! If you cannot do that, then you must free them so that they find their food by going around on the earth!” When he reached near the door, he tied a shawl around his girdle and recited two couplets of Ruhayhah al-Ansari:
Fasten you riddle for the death
Because the death is coming before you
When death comes
Do not show unease!
 Al-Sawā`iq al-Muhriqah, Page 134
Ummu-Kulthūm bid adieu to her father with tears in her eyes. Imam al-Hasan (a.s) wanted to go to the Mosque with the Imam, but he asked him not to come. When he reached the Mosque, there was darkness there. He offered a few genuflections of prayer in the darkness. After reciting the supplications, the reddish dawn was around. He then went to the place from where the adhan is sounded and called the Faithful to prayer! This was the last time that his voice resounded calling the people to pray and was heard in every household of al-Kūfah. Then he went round calling “Come to prayer! Come to prayer,” waking people for the prayer. Among these people was Ibn Muljim as well. The Imam (a.s) found him sleeping face down and said, “This is the way the Satan sleeps! Sleep on your left shoulder which is the way of the believers or sleep on the right shoulder that is the wont of the scholars, or sleep with you face up that is the way the Prophets sleep! Get up and pray. I know with what purpose you have come here and what you have hidden under the lapel of your cloak!”
After awaking people, the Imam (a.s) stood in the arch for the prayer. When he raised his head from the first prostration of the morning’s optional prayer, Shabib ibn Bajrah attacked with his sword, but the sword hit the pillar of the Mosque and the attack went in vain. Then Ibn Muljim hit his poisoned sword on the head of the Imam (a.s) that cracked his skull. The Imam (a.s) immediately said, “In the Name of Allah; and on the Religion of Allah’s Messenger. I have really won. I swear it by the Lord of Ka`bah! O People! The son of the Jewess, Ibn Muljim, has killed me.”
The Imam (a.s) is like the spirit of the world. When the spirit is hurt the limbs and other parts are affected. Therefore, at that time the sky shivered and the earth had a cataclysm! The doors of the mosque dashed against each other. The following words were heard between the earth and the sky, “The pillars of the True Guidance have actually been demolished; and the Firmest Handle has split! By Allah! The cousin of the Prophet has been killed! The successor of the Prophet has been killed! `Ali the Well-Pleased has been martyred!” This sound shook up the people of the city of al-Kūfah. People started arriving at the Mosque in hordes. Imam al-Hasan and Imam al-Husayn ran towards the Mosque in panic where the people were crying inconsolably and were shouting, “Amir al-Mu’minin has been martyred!” The sons of the Prophet (a.s) went forward and saw that the arch of the Mosque was immersed with blood and the Imam (a.s) was restlessly turning on the floor in blood and dust. He was picking up the dust from the floor, putting it on his injured skull and reciting the following verse:
مِنْهَا خَلَقْنَاكُمْ وَفِيهَا نُعِيدُكُمْ وَمِنْهَا نُخْرِجُكُمْ تَارَةً أُخْرَى.
“From it We created you and into it We shall send you back and from it will We raise you a second time. (20/55)”
Seeing the face and the head of Amir al-Mu’minin (a.s) covered with blood, Imam al-Hasan (a.s) said with choking voice, “Father! Who has shed your blood?” The Imam (a.s) lifted his head, looked at Hasan (a.s) and said, “My son! First, offer your prayer!” Therefore Imam al-Hasan (a.s) led the congregation and `Ali (a.s) sat there in prayer. After the prayer, the Imam (a.s) was brought to the courtyard of the Mosque. People had already gathered in large numbers inside and around the Mosque. Every eye was wet with tears and every heart was saddened. When Imam al-Hasan (a.s) inquired about the killer, the Imam (a.s) said, “I have been killed by Ibn Muljim al-Muradi” He pointed towards the door, Bab-Kindah and said that. “He will just be brought through that door!” Some persons were just then seen dragging Ibn Muljim in through that door. People started shouting, “Ibn Muljim has been apprehended!” The crowd was getting restless with anger and anguish. Every person was cursing him.
When he was brought before Imam al-Hasan (a.s) he told the wretch, “O unfortunate accursed person! You have killed Amir al-Mu’minin (a.s)! Is it the return for the kindnesses that he showered on you people?” Ibn Muljim stood there with bowed head and did not give any reply. `Ali (a.s) opened his eyes in delirium and looking at him said, “O Ibn Muljim! Was not I your good Imam? Were my kindnesses worth forgetting?” At this Ibn Muljim said, “Will you get one released who has made the way for the Hell?” Then the Imam (a.s) turned towards Imam al-Hasan (a.s) and said, “O son! If I remained alive, it will be my prerogative whether I punish him or pardon him! If I pass away because of this injury, you must kill him only with one stroke. After killing do not sever his limbs! I have heard the Prophet (a.s) say, ‘Beware! Do not do cutting off the limbs of anyone. Even if it is a dog!’ During the days of his captivity give him the food that you yourself eat and drink!”
Now people carried the Imam (a.s) home on their hands. Outside the house there was loud lamentation. Hearing these sounds Imam al-Hasan (a.s) came out and told the people, “Amir al-Mu’minin (a.s) is asking you to go to your homes!” Al-Asbagh ibn Nubatah says that the people disbursed but his heart would not allow him to go without seeing the Imam (a.s). He kept standing there. When Imam al-Hasan (a.s) came out again, he said, “O Son of the prophet (a.s)! I would not like to go without seeing Amir al-Mu’minin (a.s).
Please allow me one glimpse of him!” Imam al-Hasan (a.s) went inside and emerged after some time and took al-Asbagh inside. He saw the Imam (a.s) had a yellow cloth tied around his head His face too had turned yellow with weakness and loss of blood. He could not distinguish between the color of the bandage and the Imam’s face. He could not control himself and started crying.
When the Imam (a.s) saw al-Asbagh crying, he said, “O al-Asbagh! Do not cry! I am going towards the Heaven!” He said, “O Amir al-Mu’minin! I know you will go to the Heaven! But I cry because I am getting separated from you! Now who will take care of us? Who will help the orphans and the widows?”
Saying this, al-Asbagh stood up and the Imam (a.s) went into a delirium with weakness. He was now alternating between delirium and senses. Imam al-Hasan (a.s) gave him a bowl of milk. The Imam (a.s) drank a little and left the rest. He said that Ibn Muljim too should be given a beverage of milk. In that time the physicians of al-Kūfah had assembled. Among them was the famous surgeon and physician, Athir ibn `Amr al-Sakūni. After inspecting the wound he said it was mortal and that there was not any chance of survival. The poisoned sword had penetrated the brain and the venom had spread. Hearing this, the hearts of the people there started sinking. And tears started flowing from their eyes. The Imam (a.s) spent the nights of 19th and 20th of Ramadan in great pain. When two thirds of the twenty-first night was gone, the condition of the Imam (a.s) became very precarious and droplets of the sweat of death appeared on his forehead. He recited the shahadah and breathed his last! The one who spent his life doing jihad against the forces of evil, ultimately died at the hands of the evil Ibn Muljim!
Murder is a serious crime, but the consequences of the murder depend on the status of the victim and similarly the punishment too varies from case to case. An ordinary person’s killing is a crime and the killing of a believer is a bigger crime and according to the Nass of the Qur’an the punishment for the perpetrator of the crime is perpetual burning in the Hellfire. Then killing of Amir al-Mu’minin (a.s) was a great calamity and the killer qualified for Allah’s curse and perpetual retribution! This was the killing of the person who used to spend his nights in supplication to Allah! The killer neither considered the sanctity of the Mosque nor thought that he did the heinous act when the Imam (a.s) was in his prostration. One sad aspect of this tragedy is that when this happened, the Imam (a.s) had already mobilized a big contingent of troops and was to leave for Syria soon to fight with the forces of evil. It is quite possible if there was a conspiracy behind the assassination. When a tributary could be used to poison Malik al-Ashtar and Ju`dah bint al-
Ash`ath too is used to poison Imam al-Hasan (a.s), it is quite probable that the same forces of evil might have used Ibn Muljim to commit this heinous crime. The person, Ibn Muljim, was the most villainous character. The Prophet (a.s) had compared the assassin of `Ali (a.s) to those who killed the she-camel of Prophet Salih. Therefore, Ja`far ibn Samarah says:
The prophet (a.s) said to `Ali (a.s), “Amongst the bygone people, the most callous was that who killed the she-camel of Prophet Salih.”
The prophet (a.s) was asked by `Ali (a.s), “Who is the most callous in the latter days?”
He said, “Allah, and His Prophet know that he is your assassin.”
If the killer of the she-camel of Prophet Salih deserved Hellfire, then how could the killer of `Ali (a.s) escape Hellfire, when both had extinguished the miracles of the prophets and erased the verses of Allah! After this, there is no weight in Ibn Hazm saying that this killing was the result of (error of interpretation). One cannot lighten the sin of the person and term him deserving of Allah’s Forgiveness and Blessings!
The twenty-first night of Ramadan was in its last stage. The dull radiance of the moon was pervading the environment, the stars were twinkling and there was silence in the abode of Imamate. On one side were the close relations of the Imam (a.s) and on the other were his Companions. They were all a picture of sadness and pathos. Arrangements were being made for the final bath and giving him the shroud. Imam al-Hasan and Imam al-Husayn (a.s) gave him the bath in a way that Imam al-Husayn (a.s) was pouring the water and Imam al-Hasan (a.s) was rubbing the body. According to one narration, Muhammad ibn al-Hanafiyyah was pouring the water and Imam al-Hasan and Imam al-Husayn (a.s) were rubbing the body. After the bath, the camphor that was left over after the final bath of the Prophet (a.s) was embalmed on the Imam’s body. Then the body was shrouded with a white cloth. According to the wish of the Imam (a.s), his mortal remains were buried the same night he died. The bier was taken to the western side of al-Kūfah towards al-Hirah.
When it reached Najaf near al-Hirah, the bier was put on the ground and Imam al-Hasan (a.s) led the funeral prayer with five or seven Takbirs. Al-Daynawari writes:
“`Ali was buried and al-Hasan offered the Funeral Prayer with five Takbirs.”
After the funeral prayer, between the white hills, at one place, they removed the soil and found a grave ready. Imam al-Hasan and Imam al-Husayn, Muhammad ibn al-Hanafiyyah and Muhammad ibn Ja`far entered the grave and the body was lowered into it. The grave was then closed with bricks and earth was poured over it and brought to the level of the ground.
In the desert of Najaf, the body was quietly consigned to the grave and people learned about this when Imam al-Hasan and Imam al-Husayn (a.s) and other close persons returned to al-Kūfah. Gossip started among the populace. Some said that he had been interred inside the Dar al-Imarah, others said that he had
 Al-Akhbār al-Tiwāl, Page 216
been buried in the al-Kūfah Mosque. Some were of opinion that the burial was done in al-Rahbah al-Kūfah and many thought that the body was taken to the locality of Karkh in Baghdad. But the correct location of the grave was known only to the sons of the Imam (a.s) and some close Companions who were in the funeral procession. One reason for keeping the location of the grave secret was that they feared barbarous acts from the Khawarij and the Umayyads that was witnessed at the Battle of Uhud when the limbs of the martyrs’ bodies were severed by the barbarous Umayyads. When the period of Banū-Umayyah was over, during the reign of Abul-`Abbas al-Saffah, Imam Ja`far al-Sadiq (a.s) came to Iraq and informed about the location of the grave to his Companions, Abū-Basir, `Abdullah ibn Talhah, the freed slave of Ibn Khunays, Yūnus ibn ²abyan and Zurarah… etc. Then commenced the visits by the Shi`ah from all over the world.
Through the confirmation of Imam Ja`far al-Sadiq and other Imams, it is established that the last resting place of Amir al-Mu’minin (a.s) is the holy city of Najaf which is a place of pilgrimage from the `Abbasid reign and the scholars of the Ahl al-Sunnah too have mentioned clearly about the location. Therefore, Ibn al-Athir writes:
“The correct belief is that his grave is the same that is visited by the masses for pilgrimage and is a source of felicity for the people.”
Ibn Abil-Hadid writes that Abul-Ghana’im Muhammad ibn `Ali, who died in 510 H, used to say:
“In al-Kūfah, three hundred Companions died, but other than the grave of Amir al-Mu’minin, the grave of any other Companion cannot be traced. The Imam’s grave is the same that is visited by people for Ziyarah.”
Amir al-Mu’minin’s martyrdom was a calamitous event in the annals of the history of Islam. Al-Kūfah, where this tragedy took place, was a picture of sadness. In the eyes of the next of kin of the Imam (a.s) the world had seemed dark and desolate. The enthusiasm of the companions of the Imam (a.s) was shattered and their peace of mind was disturbed. Even the enemies acknowledged the personality and character of the Imam (a.s).
A few statements of tribute are mentioned hereinafter:
Imam al-Hasan (a.s), giving a sermon after the burial of the Imam (a.s), said:
“You have assassinated a venerable person in the night on which the Holy Qur’an was revealed, `Isa (a.s) was taken away to the Firmament and Yūsha` ibn Nūn was killed! By Allah! The forbears could not surpass him and those after him will not achieve his status!”
`Abdullah ibn `Abbas said:
“By Allah! The world in his eyes was less valuable that the strap of the footwear! He was a tiger in combat and a river (of eloquence) in gatherings; in the company of scholars he was a paragon of wisdom! It is a pity he is no more. But he has achieved elevated position in the Hereafter!”
Sa`sa`ah Ibn Sawhan put his hand on the grave of the Imam (a.s) and said:
“I plead with Allah to bless us that we tread his foot prints, act on his example; be friends of his friends and antagonists of his enemies! O Allah! May our end be in the party of his friends! The status that he had none else could reach. The place he was in was not in the fate of anyone else!”
 Al-Kāmil fit-Tārīkh, Vol 3, Page 201
 Bihār al-Anwār
When Mu`awiyah heard of the assassination of Amir al-Mu’minin (a.s) he said:
“With the death of Ibn Abū-Talib the Fiqh and knowledge has come to an end.”
When `A’ishah got the news of the Imam’s demise, she said
“Now the people of Arabia can do anything! There is none now who could stop them!”
 Al-Istī`āb, Vol 3, Page 45
 Al-Riyā¤ al-Na¤irah, Page 230
THE END OF IBN MULJIM AND HIS COHORTS
There were four persons involved in the assassination of Amir al-Mu’minin (a.s): `Abd al-Rahman ibn Muljim, Qatam bint Akhdar, Shabib ibn Bujrah, and Wardan ibn Mujalid. When there was pandemonium in the Mosque after the act, and the people advanced towards the arch of the Mosque, Wardan ran away to his house. One of his relatives, on knowing of his involvement in the assassination, killed him with his sword! Ibn Muljim had run out after inflicting the mortal blow on the Imam (a.s). When the people saw him running away, they chased him. He threatened them that he would kill them if they went near him. But one person from the tribe of Hamdan and Mughirah ibn Nawfal succeeded in apprehending him and brought him back to the Mosque. He was kept under captivity until Amir al-Mu’minin (a.s) was laid to rest. When Imam al-Hasan (a.s) came back to al-Kūfah after the funeral, he asked for Ibn Muljim to be brought to his presence. He told him, “O enemy of Allah! For what crime you have killed Amir al-Mu’minin? Did he ever ill-treat you? “He said,” I had sworn to Allah that I would kill him. Therefore, I killed him! Now you have the right to claim qisas or to leave me free! If you give me amnesty I shall kill Mu`awiyah and remove your care forever.” Imam al-Hasan (a.s) said, “You deserve that you must be executed!” Therefore he ordered him to be executed. Haytham bint al-Aswad al-Nakha`iyyah claimed his body for the last rites. The body was given to her. She lighted a pyre and burned the body. Then the uncontrollable crowd went to the house of Qatam. She was killed; her body was rendered to shreds and burned. Her house was looted.
Shabib ibn Bujrah was hiding in the crowds and saved himself. When Mu`awiyah visited al-Kūfah after assuming power, Ibn Bajrah met him. To get into good books of Mu`awiyah he said that he was an accessory of Ibn Muljim in the assassination of `Ali (a.s). When Mu`awiyah heard this he got up in anger and told the people of his tribe that if he saw Ibn Bajrah in al-Kūfah, they will all be executed. He asked them to exile him from al-Kūfah. Hearing this he escaped from al-Kūfah in the darkness of the night. When Mughirah ibn Shu`bah was the emir of al-Kūfah, ibn Bajrah and his companions were killed fighting with the troops of Ibn Shu`bah.
source : http://www.imfi.ir/