This is according to Emad Afroogh, a sociologist and religious researcher speaking in a series of sessions to introduce the thoughts of Imam Ali (AS). Here is a summary of the third session:
The third Khutba (sermon) of Nahj al-Balagha criticizes the conditions of the time and the move by some to act against what the Holy Prophet (PBUH) had willed. It is of course possible that this Khutba has been related to the issue of Khilafat (successorship) of the Holy Prophet (PBUH). But regardless of that, the Khutba should be reflected on in terms of how Imam Ali (AS) views governance.
In part of the Khutba, Imam (AS) says: “... I put a curtain against the caliphate and kept myself detached from it. Then I began to think whether I should assault or endure calmly the blinding darkness of tribulations wherein the grown up are made feeble and the young grow old and the true believer acts under strain till he meets Allah (on his death). I found that endurance thereon was wiser. So I adopted patience although there was pricking in the eye and suffocation (of mortification) in the throat. I watched the plundering of my inheritance …”
These words ad these Khutbas should be the lesson for every government that wants to follow in the footsteps of Imam Ali’s (AS) government.
In another part of this Khutba, Imam (AS) says: “(A ruler) was like the rider of an unruly camel. If he pulled up its rein the very nostril would be slit, but if he let it loose he would be thrown. Consequently, by Allah people got involved in recklessness, wickedness, unsteadiness and deviation.”
In different parts of Nahj al-Balagha, Imam (AS) warns rulers not to force the weak to do things against their will nor use coercion and threats against them. Ruler should only monitor and control the affairs in society.
The Commander of the Faithful looks at governance as a means for reaching an end and that end is not being indifferent to the hunger of the oppressed while the oppressors are accumulating wealth.
Imam Ali (AS) clearly says that if God has not made a covenant with him and with scholars not to be indifferent to these issues, he would abandon being Caliph.
From the third Khutba of Nahj al-Balagha one can derive the theory of legitimacy, a legitimacy that is the combination of two elements: rightfulness and acceptability (popularity). Imam Ali (AS) has rightfulness and religious legality but before people coming to him and pledging allegiance with him, the element of legitimacy had not been materialized. So legitimacy has two components: rightfulness and acceptance (by people).