In response to this...
In response to this, Imam Ali (PBUH) said the following: “Because these people were invited to allow the Qur’an to judge among ourselves, we were not a group that turned away from the Book of Allah, as He has said that “if you dispute concerning anything, refer it to Allah and the Apostle.” And referring it to Allah is to accept His Book as a judge, and referring it to the Messenger’s Sunnah is to accept his Sunnah (practice).
If they truly judge with Allah’s Book, we are more deserving of it than other people. The opinion of your leaders was unanimous to accept two men as arbitrators, and we obtained an agreement from those two to take the Qur’an as a yardstick and not to exceed its rulings. Their tongue should be with the Qur’an and their hearts should follow its ruling. But those two disobeyed the Qur’an and gave up the truth while they knew it.
They desired to get out of the right path and their mood was to deviate and oppose what pleases Allah.” At that point, they withdrew from Ali’s army and came to the house of Abdullah son of Wahab al-Rāsibī in a place called Harura. Abdullah gave them a sermon and invited them to piety and enjoining of good deeds and forbidding of evil.
Then he said: “Get out of this city whose people are oppressors and seek refuge in the cities and places in the mountains and do not accept this heresy.” Thus, they said: “This gathering became greater and, in that assembly, they pledged allegiance to Abdullah son of Wahab. From there, they went to Nahrwan and invited the people to join their group.” Thereafter, they started killing people.
They killed Abdullah ibn Khabbab, whose father was a companion of the Messenger of Allah, and opened the stomach of his pregnant wife. When the news reached Ali, he said to the people of Kufa: “How can we leave them alone and go to Syria?
It is better to make our mind at ease on the side of the Kharijites, thereafter rush towards Syria.” On the other hand, the Kharijites of Basra, whose number was documented as five hundred men, joined the Kharijites of Nahrwan, and their number increased and their danger became more serious.
Ali went after the Kharijites with his troops, but as it was necessary for his guidance and kindness before the war broke out, he sent Abdullah son of Abbas to them and told him :” Do not use the Qur’an as an argument against them because the Qur’an has different meanings. You will say something and your opponent will say something else.