War broke out between the two groups at the famous Battle of Siffīn (1) in Dhu al-Hijjah of 36 AH. The two sides fought more than seventy engagements, in which approximately seventy thousand men from both sides were killed (2).
Neither Ali nor Muāwiya wished for the fighting that took place between them. Rather, influential men driven by their own passions were present in both armies and incited them to fight. This led to the outbreak of those devastating battles and caused matters to slip beyond the control of Ali and Muāwiya (may Allah be pleased with them both).
Shaykh al-Islām Ibn Taymiyya said: “Most of those in both groups who favored fighting obeyed neither Ali nor Muāwiya. Ali and Muāwiya (may Allah be pleased with them both) were more intent on preventing bloodshed than most of the combatants, but they were unable to prevail amid the events that unfolded. Once turmoil erupts, even the wise are powerless to extinguish its flames.
“Among the two armies were men such as al-Ashtar al-Nakhaī (3), and Hāshim ibn Utba