After he died , people followed ` Abdu ` l-Bah Ã . BahÃ ` u 'll Ã h had written that ` Abdu ` l-Bah Ã had special powers , and that God would make sure that if ` Abdu ` l-Bah Ã explained anything that BahÃ ` u 'll Ã h said , then the BahÃ ' Ã s should believe that explanation . The canonical texts are the writings of the BÃ b , BahÃ ` u 'll Ã h , ` Abdu ` l-Bah Ã , Shoghi Effendi and the Universal House of Justice , and the authenticated talks of ` Abdu ` l-Bah Ã .