In circa 688/89, Abd al-Malik tasked Aban with suppressing the rebellion of the Qaysi chieftain Zufar ibn al-Harith al-Kilabi, who, from his fortified, strategic outpost of al-Qarqisiya on the Euphrates, posed an nagging obstacle to the caliph's planned conquest of Iraq. That province was controlled by Mus'ab ibn al-Zubayr on behalf of his Mecca-based brother, Abd Allah, a rival caliph to Abd al-Malik. Zufar recognized the suzerainty of Ibn al-Zubayr and had previously staved off the Umayyad commander, Ubayd Allah ibn Ziyad, in 685/86.