Who or what is "Zaabalwi"?

The story "Zaabalwi" by Nagub Mahfouz is about a narrator's quest for Zaabalwi. The story takes place in Cairo and the narrator looks everywhere to find the mysterious character Zaabalwi. The narrator is looking for Zaabalwi because he has a disease, which no doctor can cure, and he believes Zaabalwi can heal him. The people of Cairo refer to Zaabalwi as a saint, who possess physical healing, and religious salvation. The narrator first hears about …

…he was drunk and we dreaming. Although Zaabalwi disappeared as usual and no one knows his next return, the narrator is encouraged by his dream and determined to continue his search for Zaabalwi Zaabalwi is a saint in the Cairo society and he posses healing powers. Few people have met him in person but for those that meet him, he felt a lasting impression on them. He was very religious and a very good man.