What is the ruling on one who reviles the Rightly Guided Caliphs (Abu Bakr, Umar, and Uthman) under duress and threat of death?

If a person is forced to insult the honorable Companions and threatened with death if he does not comply, then there is no blame or sin upon him for that. For whoever is compelled to disbelieve is not held accountable for it, as stated in the verse: "Except for him who is compelled [to recant] while his heart is firm in faith," and the saying of the Prophet, peace and blessings be upon him: "Indeed, Allah has overlooked for my nation mistakes, forgetfulness, and what they are compelled to do." Thus, what is done under compulsion is not held against the one who does it, as long as his heart rejects and disavows it.