On the day Ameerul Momineen (a.s.) was struck down, Jibrail (a.s.) was heard by every wakeful person calling out between the skies and the earth – By Allah, pillars of guidance have been destroyed, and by Allah, stars of the sky and signs of piety have been obliterated, the reliable rope has been broken, Muhammad al-Mustafa’s (s.a.w.a.) cousin has been killed, the chosen successor has been killed, Ali al-Murtaza has been killed. By Allah, the chief of the successors has been killed. The most wretched of the wretched has killed him.
Behaar al-Anwaar v 42 p 280