Hilyat Al Awliyaa wa Tabaqaat al Asfiyaa.
In this work, the author gathers the biographies of the Imaams of the righteous - beginning with the generation of the Sahaabah and downwards. He mentions the Ahadeeth they narrated along with their own statements.
He collected more than 800 biographies starting with the four Khalifahs, moving on to the ten who were given the glad tidings of paradise, then the rest of the companions and those who came after them down to his own generation.
He mentions narrations with their chains of narration.
Adh Dhahabee stated: “The likes of Hilyat al Awliyaa has never been authored.”