Letter 64, written by Imam Ali (a.s.) to Muawiya, is a significant historical document that reflects a delicate period in Islamic history. This letter was written at a time when political differences among Muslims were escalating, particularly between Imam Ali (a.s.) and Muawiya ibn Abi Sufyan. In this letter, Imam Ali (a.s.) clearly states that there was a unity between them before the advent of Islam, but this unity was shattered due to the acceptance of faith. This letter serves as a testament to Imam Ali's (a.s.) clear distinction between truth and falsehood.

At the beginning of the letter, Imam Ali (a.s.) emphasizes that the division arose from their acceptance of faith. He also mentions that those who converted to Islam did so under duress, while he and his followers remained steadfast on the truth. This conveys the lesson that unity and division can arise from the foundation of faith. Imam Ali (a.s.) responds to Muawiya's accusations by stating that his actions do not require any justification on Muawiya's part.

Imam Ali (a.s.) also suggests that if Muawiya is eager for war, he should exercise patience, and if he wishes to meet, Imam Ali (a.s.) may come to him. This demonstrates Imam Ali's wisdom and patience. He further asserts that he possesses the same sword that has already claimed the lives of Muawiya's relatives, indicating his strength as a leader.

Imam Ali (a.s.) points out the limitations of Muawiya's intellect and the flaws in his intentions. He makes it clear that Muawiya has climbed a ladder that leads to a dire situation for him. This imparts an important moral lesson that individuals should reflect on their intentions and actions.

In conclusion, Imam Ali (a.s.) advises Muawiya to first enter his allegiance, and then he can file a case against the killers of Uthman in his court. This reflects Imam Ali's commitment to justice and principled behavior. This letter is not only a historical document but also contains significant moral and spiritual lessons.