Transfer of Imamate from Imam Hussain to Imam Ali Al-Sajjad

The transfer of the Imamate to the next Holy Imam has to occur at the death of the previous Holy Imam, and the transfer of the Imamate of Imam Hussein to Imam Sajjad was under particularly distressing circumstances with the severe illness that Imam Sajjad was suffering and the martyrdom of so many family members and companions.