Answer
Rasulallah ( saw ) informed us of the different categories of saintly
persons. For example the Abdaals, the Masaaib, and the Nujabaa. Abdaal is the
plural of Badl and when any one of the forty Abdaals pass away, he is
immediately replaced by another saintly person. (Abu Dawood)
And Allah Ta’ala knows best
Mufti E. Desai