He was also the one who founded the “office of propagation”...

He was also the one who founded the “office of propagation” which was later imitated by the ‘Abbasids.[^15] When the Umayyad caliph Sulayman ibn ‘Abd al-Malik felt threatened by Abu Hashim, he invited him to Sham and poisoned him.

When Abu Hashim realized that that was his end, he went to Hamimah, the living place of his ‘Abbasid cousins, declared Muhammad ibn ‘Ali al-‘Abbasi as his successor, and introduced to his successor his preachers and forces.[^16] From then on, the Banu ‘Abbas assumed the leadership of the followers of Kaysaniyyah and focused their activities in Khurasan.

As Abu’l-Faraj al-Isfahani says, The people of Khurasan believed that Abu Hashim was the successor of his father and that his father inherited the right of succession { wasayah } from his father (viz., ‘Ali ( ‘a )). He in turn appointed Muhammad ibn ‘Ali al-‘Abbasi as his successor and who, in turn, designated…