Fortress of the Muslim by Sa'id Bin Ali Bin Wahf Al-Qahtani is arguably the most famous anthology of Adkhar and Dua's of the Messenger of Allah (s). The original compilation is one of the most authentic collections available and has become the most popular dua book in the Muslim world today. Making dua to Allah frequently and with full submission has many benefits - it increases iman , gives hope and relief to the distressed, and saves the supplicant from despair and isolation.