Allamah Majlisi (a.r.) narrates from Rejaal al-Kashi that:
Imam Hasan al-Askari (a.s.) came out of his house for the funeral of his blessed father Imam Ali Naqi (a.s.) in a manner that his shirt was ripped (from the front). Upon seeing this, a man named Abu Aun al-Abrash wrote a letter to the Imam (a.s.) asking him:
“Who have you seen or has any one of the other Imams torn their shirts in a manner like you did?” In another narration it is mentioned that this man also wrote: “People were horrified to see you like this.”
In his response to this disrespect, Imam Hasan al-Askari (a.s.) wrote back to him:
“O fool! What do you think of yourself? Surely Prophet Musa (a.s.) had ripped his shirt in this manner when Prophet Haroon (a.s.) passed away.”
Imam (a.s.) further wrote,
“Surely among the people, there are some who are born as believers, live their lives as believers, and depart from this world also as a believer…”
“…But there are some others who are born as believers, live their lives also as believers, but die as a disbeliever.”
“Certainly, you will not leave this world till you become a disbeliever and lose your intellect.”
Just like the Imam (a.s.) had predicted, that man departed from this world in a state that his own children locked him in a room, away from the eyes of other people due to his loss of intellect, (satanic) whispering, mixing things while speaking, his opposition to the people of Imamat, and because of his hypocrisy becoming evident.
[Behaar al-Anwaar, vol. 50, p. 191, H. 3 & 4 narrating from Rejaal al-Kashi, pp. 479-480]
▪The interesting part in this narration is that the man went crazy as a punishment for doubting the actions of an infallible Imam and because he disbelieved in Imamat, his end was on disbelief.
▪Hence, it should be clear for anyone who objects to performing chest-beating (Maatam) in this manner with a ripped shirt that mourning in this manner is a practice (Sunnah) of both, the Prophets (a.s.) as well the Imams (a.s.).
Surely, Our Master Imam Hasan al-Askari (a.s.) has said the truth.