Complex sentence: When he became seriously ill, a group of Shia elite went to see him and about the next deputy; he replied; Husayn b. Ruh is my successor and the trusted deputy of the Master of the Age.
Split into simpler sentences: When he became ill seriously, a group of Shia elite went to see him. He answered them: Husayn b. Ruh is my successor and the trusted deputy of the Master of the Age.