Caliph ʿUmar b. al-Khaṭṭāb (r.634-644), the second successor to Prophet Muhammad, told Kaʿb al-Aḥbār to narrate what he read in the holy books to the people of Medina, right after the latter’s conversion from Judaism to Islam. Kaʿb is a semi-historical figure, who, according to the Islamic historiographical tradition, transmitted many biblical stories from Judaism and Christianity to Islam. According to this brief account, found in al-Wāqidī’s Futūḥ al-Shām (The Conquest of Syria), he met ʿUmar in Jerusalem, converted to Islam and returned to the Hijaz with him. In Medina ʿUmar asked Kaʿb to preach his knowledge of the holy books to public, and Kaʿb agreed. Inspired by this story, the current paper analyzes the act of hagiodiegesis, the practice of narrating stories about sanctified people to a public audience, in the early Islamic era, roughly defined as until the end of the Umayyad Caliphate (750 CE). In light of various examples of early Islamic literature, it explores the circumstances under which this practice took place and who its agents were. Bridging between the wider discussions on hagiography and oral tradition, this paper presents a social history of particularly slaves and converts as builders of the Islamic notion of sanctity, through various form of hagiodiegesis, such as waʿaḍ and qaṣṣ. Analyses of oral aspects of Christian hagiography in late antiquity and the Middle Ages demonstrate that hagiographical stories were orally circulated and aurally consumed in urban, semi-urban and monastic contexts. Widespread practices of reading out loud, preaching and narrating stories of holy men and women found direct continuation in the early Islamic communities. Despite coming with significant methodological problems, which also will be addressed in this paper, the study of the practice of narrating stories about sanctified people contributes greatly to our understanding of the formation and development of hagiographical traditions in Islam.