How did Imam Ali (a.s.) treat his enemies and opponents?
One of the characteristics of the political behavior of the Commander of the Faithful (a.s.) was that he used to reason with his enemies and opponents. He even used to reason with Muawiyah in his correspondence with him. Although the enmity between Muawiyah and the Commander of the Faithful (a.s.) was fierce, Muawiyah used to write letters to the Commander of the Faithful (a.s.) in which he used to insult him and say things which were not true.
After Talha and Zubair pledged allegiance to the Commander of the Faithful (a.s.), they got out of Madina and went towards Makka with the excuse that they intended to go on a hajj pilgrimage. The Commander of the Faithful (a.s.) was vigilant. From the beginning, he used to say that they do not intend to go on a hajj pilgrimage. They went and hatched certain plots. Of course, it is a long story why they did this.
Hazrat said, "Both of you frown over a small matter and leave aside big ones" [Nahjul Balaghah, Sermon 204]. He said that they used a small matter as a tool to create discord, that they ignored many positive points and that they intended to show enmity and disobey his commands. Despite these things, the Commander of the Faithful (a.s.) spoke in a humble way to them. He explained that he was not after creating enemies for himself. So, he showed tolerance.
But when tolerance is not sufficient, there is room for Alavi decisiveness. For example, he showed his decisiveness towards the Khawarij in such a firm way that he himself said, "I tore out the eye of fitna" [Nahjul Balaghah, Sermon 92]. And no one else could do this except for Ali, as he himself said in Nahjul Balaghah.