This supplication has been recited to Prophet Muhammad (PBUH) during one his battles.[In that battle] the Prophet had a very heavy coat of armor on to protect himself. The coat was so heavy that it was hurting the Prophet's body. In this state, the Angel Gabriel came to the Prophet and said, "O Muhammad! Your Lord conveys his salutations to you and tells you to take out this coat of armor (jawshan) and to recite this dua [instead], as it is a protection for you and your Ummah." Its highly recommended to read this supplication on the Qadr nights.