Either Fergus or David—or perhaps both Fergus and David—may have been responsible for the foundation of the abbey of Dundrennan, a Cistercian house situated well within the confines of Fergus's lordship. John Fordun and Walter Bower accord its foundation solely to David, although the near contemporary John Hexham failed to note the house amongst David's known foundations. The fact that Walter Daniel, a Cistercian monk from the community at Rievaulx, was highly critical of Galloway and its inhabitants may be evidence that Fergus was unlikely to have been the sole founder. David's own close connections with the Cistercians could suggest that the monastery owed its formation, as a daughter house of Rievaulx, to cooperation between David and Fergus.