Mourning the Death of Husayn ibn Ali?

The best that can be said when remembering these and similar calamities is that which ‘Ali ibn al-Husayn narrated from his grandfather the Messenger of Allah(pbuh) 

, who said: “There is no Muslim who is afflicted by a calamity and when he remembers it, even if it was in the dim and distant past, he says Inna Lillahi wa inna ilayhi raaji’oon (verily to Allah we belong and unto Him is our return), but Allah will give him a reward like that of the day when it befell him.”

Narrated by Imam Ahmad and Ibn Majaah, end quote from al-Bidaayah wa’l-Nihaayah (8/221).