Battle of Siffin
Then, there was the Battle of Siffin. Regarding its details, it is mentioned that it was a battle that took place between Hazrat Ali (ra) and Hazrat Amir Muawiyah (ra) in 37 AH.
Siffin is the name of an area located between Syria and Iraq.
Hazrat Ali (ra) left Kufa along with his army and when they reached Siffin, they saw that the Syrian army under the command of Amir Muawiyah (ra) had already setup camp and one section of the army had taken over a valley near the Euphrates River. Hazrat Ali (ra) assured them that they had not come to fight but instead, had come to reconcile their differences; however, Amir Muawiyah (ra) was not willing to reconcile. The Syrian army stopped the army of Hazrat Ali (ra) from accessing the water from the Euphrates River. Upon this, Hazrat Ali (ra) ordered his army to launch an attack and they succeeded in pushing the Syrian army to retreat and thus establishing their access to the river. Hazrat Ali (ra), however, allowed the Syrian army to access the water from the Euphrates River. The Syrian army had prevented Hazrat Ali (ra) [and his army] from accessing water from the Euphrates River, but when Hazrat Ali (ra) took control of the river, he permitted them to access its water.
Amir Muawiyah (ra) insisted that Hazrat Ali (ra) should hand over those who had carried out the killing of Hazrat Uthman (ra). At one point there was a potential danger that a battle was going to break out; however, some of the peacekeepers prevented this from happening and established calm.
The battle took place in the month of Safar 37 AH, but prior to the actual battle commencing, small skirmishes broke out. Yet still, both parties abstained from engaging in a full battle considering its dangerous consequences. Both parties ensured to utilise all means possible in order to bring about reconciliation and thus both agreed that they should enter a temporary agreement of peace during the sacred months. However, this effort of theirs also proved unsuccessful. And so, at the beginning of the month of Safar, the actual battle was formally declared once again.
For quite some time, the fighting continued without any conclusive victory and Amir Muawiyah’s (ra) resolve began to weaken. In such precarious circumstances, Hazrat Amr (ra) bin Aas advised that they should tie the copies of the Quran on the tip of their spears and announce that they should settle the matter in accordance with the Quran. Thus, they did exactly that and as a result a disagreement arose between Hazrat Ali’s (ra) men. A large party among them stated that their plea to adjudicate the matter by the Book of Allah should not be rejected. Subsequently, Hazrat Ali (ra) commanded the vanguard of the army to return and thus the battle stopped. The majority of the army of Hazrat Ali (ra) accepted the suggestion presented by Amir Muawiyah (ra) which was that each party should appoint an arbitrator and they should both reach a verdict based on the Holy Quran. According to the books of history, this incident is known as “Tahkim” [arbitration]. In any case, the Syrians appointed Hazrat Amr (ra) bin Aas as their representative and Hazrat Ali (ra) appointed Hazrat Abu Musa Ashari (ra). After signing this declaration, both armies dispersed.
This is a reference from the historical accounts by Ibn Athir.
(Ibn al-Athir, Al-Kamil fi al-Tarikh, Vol. 3 [Beirut, Lebanon: Dar al-Kutub al-Ilmiyyah, 2003], 161-201) (Lughat al-Hadith, Vol. 2, p. 608, Zair-e-Lafz Siffin)