The article addresses the interrelation between two manuscripts from fourteenth-century Iceland, Uppsala UB C 301 and fragmentary AM 241b Iα fol. Both contain a sermon collection, the Themata sermonum by Dominican friar Nicolaus de Gorran. From a comparison of the two, the article demonstrates that the manuscripts were closely related and had probably been copied from one another or the same exemplar. The original collection had been adapted in order to suit specific Icelandic needs, which become apparent through traces of textual reduction, selection, and expansion. The article exploits the contextualizing potential of the marginalia found in both manuscripts. It links the manuscripts to the contemporary law compendium AM 741 4to and ultimately suggests Skálholt during the episcopate of Jón Halldorsson as the possible provenance.