‘The Prayer of Manasseh’, a beautiful penitential prayer attributed to King Manasseh of Judah, has had a rich and complex textual transmission. Amongst its Syriac textual witnesses, two main versions emerge: one appearing in the Peshitta and the Didascalia, and another in the Melkite Horologion. In this study, the authors present a detailed philological and linguistic comparison of these two versions. Combining state-of-the-art computational tools together with traditional philology the texts are compared at all linguistic levels, from their vocabulary up to their discursive structure, with a special emphasis on their morphology and syntax. The results are revealing not only for the question of the relationship between the two versions, but also illuminate various debates pertaining to Syriac syntax. Questions of a methodological nature regarding textual comparison using qualitative and quantitative techniques are addressed as well. Together with the thorough text-historical and tradition-historical introduction, the book is a natural companion for anyone interested in this remarkable prayer, as well for anyone interested in Syriac linguistics, literature and liturgy.