This article deals with the question of the sources of the chapter “O liczbie a wywodzie Sybil” of M. Bielski’s chronicle, which has not yet been fully resolved. In the course of the research, we managed to identify some of them: Lactantius “Divinae institutiones”, F. Barbieri “Sibyllarum de Christo vaticinia, ex vetustiss, codice descripta”, St. Augustine “De civitate Dei”, chapter “De vita beata”. We have also made a comparative analysis of two Church Slavonic translations of this chapter, belonging to N. Spafarius and an unknown author, which also reveal continuity; most likely, N. Spafarius took the Polish text as the basis of his work, despite the fact that he did not mention it anywhere in the text.