Marwān returned from Mosul and settled in his residence at Ḥazān. He rejoiced at the disappearance of the Kharijites, yet his joy did not last, for destiny soon confronted him with an adversary more powerful, with a larger following and fiercer strength than the Kharijites: the emergence of Abū Muslim al-Khurāsānī, the propagandist for the Abbasid state.
The First Emergence of Abū Muslim al-Khurāsānī
In that same year a letter arrived from Ibrāhīm ibn Muḥammad, the Abbasid Imām, summoning Abū Muslim al-Khurāsānī from Khurāsān. Abū Muslim therefore set out to meet him, accompanied by seventy nuqabāʾ (section leaders). Whenever they entered a town the people would ask, “Where are you bound?” and Abū Muslim would reply, “We are heading for the ḥajj.” If he perceived in anyone a leaning toward their cause, he would invite him to it, and the man would accept.
When they had covered part of the journey a second letter from Ibrāhīm the Imām reached Abū Muslim: “I have dispatched to you the Banner of Victory; return to Khurāsān and make the daʿwah public.” He also instructed Qaḥṭabah ibn Shabīb to proceed with the funds and gifts in his charge to Ibrāhīm the Imām and meet him during the pilgrimage season.
Abū Muslim thereupon turned back with the letter. He entered Khurāsān on the first day of Ramaḍān and presented the letter to Sulaymān ibn Kathīr, which read: “Make your call public and do not delay.” They then placed Abū Muslim al-Khurāsānī at their head as spokesman for the Abbasid cause. Abū Muslim dispatched his duʿāt throughout Khurāsān, while the province’s governor, Naṣr ibn Sayyār, was occupied with fighting al-Karmānī and Shaybān ibn Salamah al-Ḥarūrī, whose influence had grown so great that many contingents of Kharijites greeted him with the salutation reserved for the caliph.
Abū Muslim’s enterprise now gained prominence, and people flocked to him from every direction; on a single day delegations from sixty villages came to him. He remained there forty-two days, during which many regions were opened to him.
On the night of Thursday, five nights before the end of Ramaḍān that year, Abū Muslim unfurled the standard the Imām had sent—called al-Ẓill (“the Shade”)—raising it upon a shaft fourteen cubits long. He likewise unfurled the banner the Imām had sent—called al-Saḥāb (“the Cloud”)—upon a shaft thirteen cubits long; both were black. As he did so he recited: “Permission [to fight] has been granted to those against whom war is waged, because they have been wronged; and surely Allah is able to grant them victory” (Qur’an 22:39).
Abū Muslim, Sulaymān ibn Kathīr, and all who answered their call donned black garments, which became their emblem. That night they lit a great fire as a signal to summon the people of those regions, so they gathered. One of the two banners was named al-Saḥāb because, just as clouds envelope the whole earth, so the Abbasid daʿwah will envelope its inhabitants. The other was named al-Ẓill because, just as the earth is never without shade, so it will never be without a scion of the Abbasid house. People now converged upon Abū Muslim from every quarter and his army swelled.
When the day of ʿĪd al-Fiṭr arrived, Abū Muslim instructed Sulaymān ibn Kathīr to lead the people in prayer. He set up a pulpit for him and ordered him to differ from the Umayyads and to act in accordance with the Sunnah. The proclamation was made, “The prayer! Gather for prayer!” but no adhān and no iqāmah were given, in deliberate opposition to them. He began with the prayer before the sermon, pronouncing seven takbīrs in the first rakʿah before the recitation instead of four, and five in the second rakʿah instead of three,