Is the dispute that occurred between Ali and Mu'awiyah permissible in Islam? And is it conceivable that Aisha would stand against Ali because of his advice to the Prophet, may Allah bless him and grant him peace, to divorce her in the incident of the slander (al-ifk)?

A Muslim must believe that the Companions were mujtahids (exercised independent reasoning) in their disputes. For the one who was correct, there are two rewards, and for the one who erred, there is one reward. Therefore, one should only mention them in the best light and refrain from delving into what occurred between them, as Umar ibn Abd al-Aziz said: "That was a tribulation from which Allah purified our swords, so let us protect our tongues from it." The scholars have interpreted Ali's action of delaying retribution by prioritizing allegiance to establish order, while Muawiyah sought retribution. Each intended a good outcome, so the one who was correct receives two rewards and the one who erred receives one reward. Aisha's stance was an endeavor to bring about reconciliation and justice against the killers of Uthman.