In Ashura, four thousand angels descended onto the earth in order to assist my forefather Sayyed al-Shohada, but it was not in line with the divine providence to complete their mission and to join Imam Hussain (A.S) forces in fighting against the Yazid's Army. However, up until the reappearance of the last Imam, they will remain upon Imam Hussain's temple mourning on him, and they will be among the Companions of Imam Mahdi (A.S.) whose motto is "we are the revenge seekers of Imam Hussain's blood".
As reported by the News Department of Imam Reza (A.S.) International Foundation for Culture& Arts, "Oyun Akhbar al-Reza" is one of the most comprehensive books about Imam Ali ibn Musa al-Reza (A.S) in which the hadiths of that Imam are gathered. This book is written by Sheikh Sadouq who lived one century after Imam Reza (A.S.). His grave is now located in Ibn Babuyah graveyard in Rey City in Tehran. He he was born by the merit of Imam Mahdi's (AJ) prayers. He succeeded to visit Imam Mahdi too. The book consists of four chapters including "the Hadiths narrated by Ali Ibn Musa al-Reza (A.S.), the collection of the debates of Ali ibn Musa al-Reza (A.S.) with other scholars and critics at Mamun era, collection of the Hadiths quoted by Ali ibn Musa al-Reza (A.S.) from his holy forefathers, and the debates of his father and forefathers with the scholars at their own time".
For instance, in one of the chapters of the book which is dedicated to the Hadiths narrated by Imam Reza (A.S), it reads: "He who does not follow his tasks and needs on the Ashura day, Allah will meet his needs in the world and the hereafter and he for whom the Ashura day is the day of calamity and sorrow, Allah will ordain the day of Qiyamah as the day of merry and happiness for him and he will be blessed by visiting us in Paradise. Indeed he who calls the Ashura day "the day of blessing" and stores something for that day in his abode, what he has stored will not bear any bless and in the Ressurection Day he will be re-united with yazid, Obayd allah ibn Ziad and Omar ibn Sa'd- may Allah damn them all-in the lowest degrees of the inferno".
In another hadith, Imam Reza (A.S) says: "when Muharram approached, my father was not happy anymore, sorrow and grief overcame him until the end of the first ten days and the Ashura day was the day of outmost sorrow and calamity and mourning for him".
The most famous Ashura- related Hadith narrated in "Oyun Akhbar al-Reza" might be the one derived from the Imam Reza's dialogue with "Rian ibn shabib" when Rian says: "On the first day of Muharram, I paid a visit to Imam Reza (A.S.). he inquired: "Are you fasting?" I said: "No", he said: "Today is the day when Zakariya (A.S.) invoked his Lord, and said: "Oh Lord, bestow on me a pure child, for surely you hear the prayers of your servants" and Allah accepted his prayers and ordered the angels to tell Zakariya-who was praying in mihrab-that: "Allah gives you the good tidings of Yahya"; so anyone who fasts on this day and then prays, Allah will grant his wishes the same way that the prayers of Zakariya were accepted".
We read that Imam Reza (A.S.) thus goes on to address Ibn Shabib: "If you want to weep, weep over Hussain Ibn Ali Ibn Abi Talib (A.S.) since he was slaughtered like sheep and from among his relatives 18 people were martyred along with him who were paralleled by none on earth, the seven firmaments and the earths wept over his martyrdom and 4000 angels descended onto the earth to assist him but it was not in line with the divine providence to complete their mission and to join Imam Hussain (A.S) forces in fighting against the Yazid's Army. However, up until the reappearance of the last Imam, they will remain upon Imam Hussain's temple mourning on him, and they will be among the Companions of Imam Mahdi (A.S.) whose motto is "we are the revenge seekers of Imam Hussain's blood".
Then the gracious Imam addresses his disciple: "O, Ibn Shabib! If you weep over Hussain until your tears stream down your cheeks, Allah shall forgive any sins you have committed-small or big, few or many. O Ibn Shabib! If you want to meet Allah in a purified and sinless state, go on pilgrimage of Hussain! O Ibn Shabib! If you wish to have a reward equal to that which was bestowed upon those who were martyred along with Hussain Ibn Ali (A.S.), whenever he comes to mind, say: "I wish I were with them and reached great salvation). Ibn Shabib! If you wish to accompany us in high degrees in the Heaven, be sorrowful over our sorrows and be joyous for Our joy! You must follow our Welayah (Guardianship), for if a person loves even a stone, Allah will re-unite him with that stone on the Judgement Day.