Al-Asbagh later participated in the conspiracy to kill the Umayyad caliph al-Walid II, who acceded in 743. The latter had essentially sold the champion of the Yaman, Asad's brother Khalid al-Qasri, to the Qaysi governor of Iraq, Yusuf ibn Umar al-Thaqafi, who had Khalid tortured and executed in late 743. This was perceived as a severe contempt for the Yaman by the caliph and drove many to direct vengeance against the caliph himself, a hitherto unprecedented act by the Syrian troops, the historic mainstay of the Umayyad dynasty. Al-Walid II had also run afoul of many princes of the Umayyad dynasty, particularly the sons of caliphs Hisham () and al-Walid I (). Under the leadership of al-Walid I's son, Yazid III, these dissident Umayyads and the Yaman rebelled against al-Walid II, who was slain by a Yamani troop in April 744 while his young sons and nominated successors were jailed. Al-Asbagh afterward boasted in verse:
