Ibrahim the Imam
Abu Is’haq Ibrahim Ibn Muhammad, brother of Saffah and Mansur (the first and second Abbasid caliphs). He managed Abbasids to revolt against Umayyads. His father Muhammad Ibn Ali believed that Khurasan was the only place which was suitable to accept Abbasids. The political competition among between Arab groups of Khurasan and their tendency towards Abbasids was the main reason for Ibrahim the Imam, to take notice of this city. After his father’s death, Ibrahim made Khurasanies aware that he is going to be his father’s successor, and they supported ####him. Ibrahim the Imam took two important steps, in order to achieve his political goals:
Firstly he ordered his missionaries to make people obey a person of the family’s Prophet –with no mention of a special name -, Ibrahim knew well that if his name was revealed, not only he would be arrested by Umayyad rulers but also the Shias would not obey him.
Secondly, he was going to pretend that Abbasids aim is to avenge the murderers of the Prophet’s household who were killed by Umayyad caliphs; in order to attract Shias attention.
By applying this method many people joined Abbasids. Abu Muslem was Ibrahim’s missionary in Khurasan who was supposed to kill all the Arabs in Khurasan emphatically Egyptians, But it is doubtful that, this order had been given by Ibrahim the Imam, because most of his missionaries were Arabs and he counted on his Arab supporters in Iraq and Khurasan who were against Umayyads. So this order is in contrast to Abbasids’ political aim. Abu Muslem also was the commander of the armed uprising in Khurasan.
The Arabs of Khurasan were divided into two groups: Egyptians who supported Nasr Ibn Syyar (the Umayyad emir of Khurasan) and the second group, Yemenis who supported Abbasids. Eventually Abu Muslem was arrested by Marwan Hammar (Umayyad caliph). About his death it is said that Ibrahim wrote a letter to Abu Muslem in which was ordered that all Arabs in Khurasan should be killed. Marwan saw the letter and ordered his agent in Damascus to arrest Abu Muslem.
Sources :
Islamic encyclopedia