Dua is based on the Fortress Of The Muslim (Hisnul Muslim - Invocation from Quran and Sunnah) book which compile all authentic Dua for Muslim to supplicate on a daily basis and on special occasions. Hisnul Muslim is a collection of authentic Du'a and Zikr. Some of the Du'a and Zikr topics in the app: when waking up. When wearing a (new) garment. Before undressing.