17th Safar – the Martyrdom anniversary of Imam Ali ibn-e- Moosa ar-Riza(a.s.) – the 8th Holy Imam.

His Martyrdom
Imam Ali Riza(a.s.) was summoned by Mamoon in his court and was offered some grapes which were injected with poison. Imam(a.s.) knew about it and politely declined to eat but Mamoon insisted saying that it appears that Imam(a.s.) has doubt on his intentions. Imam(a.s.) was aware from ilm-e-imamat that the time of his martyrdom has arrived and therefore ate a few grapes and left the court.
He(a.s.) arrived in Bait-ush-Sharaf. Abul Salat stayed outside on the door to guard. He mentions that he heard some conversation and movement inside so he went in to check and saw that a young lad was with Imam Riza(a.s.). He was surprised that no one had entered the room from the door so how could this young lad come in. The young lad said that he was Mohammad ibn-e-Ali Riza(a.s.) and he has been brought from Madina by Allah(swt) to take over the responsibilities of Imamat and that distances and walls are no hindrances for Imams(a.s.). When an Imam is about to leave this world, the next one stays with him to take over all the responsibilities.
Imam Ali Riza(a.s.) breathed his last after a short period and Imam Mohammad Taqi(a.s.) performed his ghusal, kafn and recited namaz-e-janaza and then instructed Abu Salat to announce the martyrdom of Imam Ali Riza(a.s.). To conceal the crime, Mamoon then organized a state funeral and mourning since Imam Ali Riza(a.s.) was a royal price as well.
The confirmation of poisoning of Imam(a.s.) by Mamoon is mentioned in the following books: Rodatus Safa, Shawahid-un-Nabuwwah, Kamil, Murawajuz Zahab, Noorul Absar, Al-Fakhri, Matalibus Suwal, Tazheeb Tahzeebul Kamal, Mukhtasar Akhbarul Khulafa and others.
Some historians such as Shibli Nomani have doubted that Mamoon would have poisoned the Imam(a.s.). It is to be noted that Mamoon never tried to investigate and punish the killers even though Imam Riza(a.s.) was the royal price and this seems strikingly strange since rules of Bani Ummaya had made a big issue out of the killing of Hazrat Usman and repeatedly had accused Imam Ali(a.s.) of involvement. Moreover, a person such as Mamoon who had killed his own brother in the name of justice did nothing to find the killers of Imam(a.s.) is a sufficient proof in itself that his character was not clean in this conspiracy.