The mosque in Gumus, a small town in the Amasya region, attracts attention because of the problem of identifying its patron. The Turkish inscription written in the Latin Alphabet "Yorguc Rustem Pasa Camisi 1426" on the plate on the portal, consubstantiating Yorguc Pasa and Rustem Pasa, identifies a historical figure who never existed as the patron of the building. This consubstantiation refers to two important actors in the construction process of the mosque: Yorguc Pasa (d. 1442), the vizier of Murad II and Rustem Pasa (d. 1561), the vizier of Suleyman I. This study does not aim to reveal whether Yorguc Pasa or Rustem Pasa was the true patron who commissioned the building, rather it aims to examine the building in detail to date its parts.