Quddús was twenty-two years old when he recognized the Báb

The last, but in rank the first, of these Letters to be inscribed on the Preserved Tablet was the erudite, the twenty-two year old Quddús, a direct descendant of the Imám Hasan and the most esteemed disciple of Siyyid Kázim. (Shoghi Effendi, ‘God Passes By’)