We said to the Messenger of Allah ﷺ on the Day of the Trench, when exhaustion had overtaken us, "Is there something we may say?"He replied, "Say, 'O Allah, conceal our weaknesses and calm our fears.'"So Allah defeated them with the wind.
قلنا الرسول الله ﷺ يوم الخندق وقد بلغ منا الجهد: هل من شيء نقوله؟ قال: قولوا: اللهم استر عوراتنا، وآمن روعاتنا. قال: فهزم الله بالريح
Bazzar narrated it in Kashf Astar (3119), from Muhammad bin Muthanna, who said, Abu Amir Abdul-Malik bin Amr told us, Zubayr bin Abdullah told us, also said to be Ibn Ruhaymah, one of the people of Madinah, from Rabih bin Abdul-Rahman bin Abu Saeed, from his father, from his grandfather, and he related it.Its chain of transmission is hasan, as detailed in the book on the biography of the Prophet, in the chapter on the Battle of the Trench.