Al-Ma’mun had fear for his kingdom and supreme authority. He was careful of that the people would break out in rebellion against him. As a result he decided to assassinate the Imam. He took some grapes and mixed them with poison, and then he asked the Imam to come. When the Imam came, he gave him a bunch of grape and said to him: “O Son of Allah’s Apostle, I have never seen grape better than this!”
The Imam looked at him and said to him: “Perhaps, there is grape better than it in the Garden!” He refused to take the bunch of grape from him. However, al-Ma’mun insisted on that and forced the Imam to have some of it. The Imam ate some of it and threw the rest away. He left the gathering, and al-Ma’mun asked him: “Where to?”
“To the place to which you have ordered me to go,” replied the Imam.
The Imam quickly went to his house. He suffered from severe pain, for the poison cut off his intestines. Meanwhile, he suffered painful loneliness and being away from his family and his homeland. Shortly after that, he passed away. That great soul ascended to its Creator! It was of Allah’s Light! Allah created it to light with it the utter darkness, to guide the perplexed, to make the oppressed secure, and to make the fearful take refuge with it. How ever, the evil, tyrannical forces put out the light of the star and deprived man of making use of its light!
The Islamic world was afflicted with that great tragedy and lost much good out of his death. The exaltedness and glory of the Muslims came to an end. They missed him who showed affection to them, was kind to them, guided them to good, and sent them far from sins and evil acts.
As for al-Ma’mun, he impatiently looked forward for the death of the Imam. When he heard of his death, he affected sadness to cover the crime and said to the people: “I hoped I died before you, but Allah refused all things except what He willed!”
He ordered him to be prepared for burial. When the Imam was washed and shrouded, he was carried to his final resting place.
The people escorted the Imam to his final resting-place in a way the like of which Khuresan never witnessed throughout its historical stages. Al-Ma’mun walked behind the great coffin; he was bare-footed and headed, saying at the top of his voice: “Your death has made a gap in Islam; Allah’s decree has overcome my decree in respect with you!”
The sacred body was brought to the graveyard. A grave beside that of Harun al-Rashid was dug for it and buried in it. Along with it was buried clemency, knowledge, and generosity. A lamp from among the Imams of guidance was buried in the land of Tus. That pure land has become sacred and reached the zenith in honor and glory, for all the Muslims had surrounded it with a halo of honoring and sacredness. Al-Ma’mun was asked about the reason for burying the Imam beside his father Harun al-Rashid, and he answered: “That may Allah forgive Harun due to his neighboring to al-Rida!” This is a weak thought, for every person is buried along with his own deeds; the honor of neighboring does not benefit him. For this reason Di‘bil al-Khaza‘i refuted al-Ma’mun, saying:
There are two graves in Tus: (The grave of the one who is) the best of all the people, and that of the most wicked of them; this is among the lessons.
The dirty one (Harun) does not take advantage of the grave of the pure one (al-Rida); and there is no harm on the pure one due to his being near to the dirty one.
How far! Every one is hostage to that which his hands earn; therefore take or leave whatever you wish!
This is the thinking of justice and truth. Harun’s nearness and neighboring to the Imam will not avail him, for his hands were stained with the blood of the progeny of the Prophet; he spread among them killing and execution, and made sadness and mourning live in their houses.