After praising Fern for receiving the legendary spell that makes clothes clean and spotless from Serie, Frieren accidentally spills food on herself. Fern uses the spell to remove the stain, which amazes Frieren and Stark. Stark dirties his clothes in the forest and tells Fern to perform the spell on him, but much to his dismay, Fern refuses to use the magic on someone that purposefully gets dirty. (thetvdb.com)