It was the obligation of everyone to rally behind him and...

It was the obligation of everyone to rally behind him and carry out his orders then make any demands. But since they all did not do so, they became oppressors like the ones referred to in the verse saying, “...then kill the one that oppresses till it returns to [accepting] Allah's Commandment” (Qur’an, Sura al-Hujurat, 49:9). Mu’awiyah scolded Sa’d Ibn Abu Waqqas[^6] for not participating in fighting ‘Ali (‘a).

Sa’d responded to him by saying that he, in fact, had only regretted his reluctance to fight al-fi'a al-baghiya (the oppressive gang), meaning Mu’awiyah and his followers.[^7] Abu Bakr, Muhammad al-Baqillani, who died in 403 A.H/1013 A.D., said the following after enumerating some of ‘Ali 's merits: “‘Ali (‘a) is qualified for the caliphate by only some of these merits and by less than these virtues, and he deserves to be the Imam. He is right in his views and in whatever he took charge of.

Obedience to him, therefore, is mandatory due to his having received the oath of allegiance from the most respected dignitaries among the Muhajirun and the Ansar on the third day following ‘Uthman's assassination. These insisted that only he was the most knowledgeable among the Sahaba , the most qualified, and the one most worthy of it. They pleaded to him in the Name of Allah Almighty to safeguard the rest of the nation and to protect Dar al-Hijra.

They, therefore, swore the oath of allegiance to him before al-Zubayr and Talhah had arrived. Having seen everyone else swearing to him, and having found themselves obligated, al-Zubayr and Talhah, too, swore the oath of allegiance to him. Had they preferred not to do so, they would have fallen in sin. Their saying to him, “We swore the oath of allegiance to you against our wish,”[^8] however, does not harm the Imamate of ‘Ali (‘a), simply because the inauguration had already been completed.

Their asking him to kill ‘Uthman's murderers prior to swearing the oath of allegiance to him was a mistake because electing a man simply so that he would kill a group of men for killing one man is not right even if his ijtihad determined that that should be the case: he may later, according to the same ijtihad , decide to do the opposite.