Imam Ali (a) in this letter has raised all the points which were once quoted against him. He says if an election on the basis of general franchise is the criterion to decide such a caliphate, then general election took place to elect him the Caliph and nobody can deny this fact, and if limited franchise (Shura) was the criterion then those who represented this group (Muhajirs and Ansars) were amongst those who elected him and therefore even according to the rules formulated by opponents of Imam Ali (a) his election was lawful, regular and bonafide. Thus no Muslim has a right to speak or act against him.
Verily, those who took the oath of allegiance to Abu Bakr, Umar and Uthman have sworn allegiance to me. Now those who were present at the election have no right to go back against their oaths of allegiance and those who were not present on the occasion have no right to oppose me. And so far as Shura (limited franchise or selection) was concerned it was supposed to be limited to Muhajirs and Ansars and it was also supposed that whomsoever they selected, became caliph as per approval and pleasure of Allah. If somebody goes against such decision, then he should be persuaded to adopt the course followed by others, and if he refuses to fall in line with others, then war is the only course left open to be adopted against him and as he has refused to follow the course followed by the Muslims, Allah will let him wander in the wilderness of his ignorance and schism.
O Mu’awiya! I am sure that if you give up self-aggrandizement and self-interest, if you forsake the idea of being alive only to personal profits and pleasures, if you cease to be actuated solely by selfishness and if you ponder over the incident leading to the murder of Uthman, you will realize that I cannot at all be held responsible for the affair and I am the least concerned with the episode. But it is a different thing that you create all these false rumours and carry on this heinous propaganda to gain your ulterior motives. Well you may do whatever you like.