The letter, ascribed to Muhammad al-Mahdi, added that the complete occultation would continue until God granted him permission to manifest himself again in a time when the earth would be filled with tyranny.
[15] Tabatabai suggests that these restrictions were placed on al-Askari because the caliphate had come to know about traditions among the Shia elite, predicting that the eleventh Imam would father the eschatological Mahdi.
[16] Immediately after the death of al-Askari in 260 (874),[17] Uthman ibn Sa'id claimed that the eleventh Imam had a young son, named Muhammad, who had entered a state of occultation (ghayba) due to the Abbasid threat to his life.
[20][21] Thus began a period of about seventy years, later termed the Minor Occultation (al-ghaybat al-sughra, 260-329 AH, 874–940 CE), during which it is believed that four successive agents acted as intermediaries between the Hidden Imam and his followers.
According to Hussain, all these suggest that al-Samarri must have faced little resistance from the Shia community later when he succeeded Ibn Ruh as the fourth agent of the Hidden Imam.
[32] The letter, ascribed to al-Mahdi, added that the complete occultation would continue until God granted him permission to manifest himself again in a time when the earth would be filled with tyranny.
[35] Ibn Babawayh and Tusi (d. 1067) both quote this final letter, parts of which are presented below: O' Ali b. Muhammad al-Samarri, may God reward your brethren in your death, which is going to take place in six days' time.