Manuscript BN 12603 III is a preaching collection including sermons, lives of saints and miracula. Among the sermons are also works on saints venerated in medieval Poland – the lives and sermons on St Adalbert and St Stanislaus, which contain information on Polish history. Glosses in Polish (in the text and marginal) indicate that the codex was written in Poland (Małopolska?) in the first half of the 15th century. However, there are some indications which suggest that the codex may have been used as a preaching aid in Lithuania.