Fortress of the Muslim (Hisn al-Muslim)
حصن المسلم
(40) Chapter: For one afflicted with doubt in his faith
(40) دعاء من أصابه شك في الإيمان
Hisn al-Muslim 134 
Āmantu billāhi wa Rusulih. (Say:) I believe in Allah and His Messengers. Reference: Muslim, 1/119-20.
يقول" آمنت بالله ورسله"
Reference : Hisn al-Muslim 134