The presented publication is a type of bibliographic dictionary, compiled by an interdisciplinary team of authors (Byzantynists and Paleoslavists), containing an overview of medieval texts referring to the person of Muhammad, the Arabs, and the circumstances of the birth of Islam, which were known in the Slavia Orthodoxa area (especially in its eastern part, i.e. in Rus'). Therefore, it presents the works written in the Church Slavic language between the 9th and the mid-16th centuries. As the Old Rus' discourse on Islam was shaped under the overwhelming influence of Byzantine literature, the majority of the presented sources are Byzantine texts from the 6th-14th centuries, translated into the literary language of the Orthodox Slavs. The reader will also find here a discussion on several relics, originally created in other languages of the Christian East (Syriac, Arabic) and the West (Latin), which - through the Greek - were assimilated on the Slavic ground. This book aims to fill a gap in previous studies on inter-religious polemics in the Middle Ages, which has usually focused on Christian-Muslim cultural relations, analyzing Greek and Latin texts or the works written in one of the Middle Eastern languages, almost completely ignoring the Church Slavic heritage. It is worth noting that a number of the texts presented here (as well as Slavic translations of Byzantine sources) have not been published so far. The information on them, provided in this monograph, is therefore the result of research conducted directly on the manuscript material.