It has been mentioned in the book, Baladal-Amin and the Misbah of Kafa’mi that Imam Ali ibn al-Hussein Seyyed as-Sijidln (prayers be upon him) related from his father from his grandfather the Prophet of Allah (blessings of Allah be upon him and his family) that this supplication was taught by the Angel Jibra'il (prayers be upon him) to the Prophet (blessings of Allah be upon him and his family) during one of the battles.
It was in one of the wars that the Prophet (blessings of Allah be upon him and his family) had taken part in which he had a very heavy and expensive coat of armor on to protect himself. It is related that the coat was so heavy that it was hurting the body of the Prophet (prayers of Allah be upon him and his family). In this state, the Angel Jibra'il (prayers be upon him) came to the Prophet (blessings of Allah be upon him and his family) and said:
"O Muhammad! Your Lord conveys his salutations to you and has said to take this coat of armor ( Joshan) and to recite it this is a protection for you and your Ummah"
At this point, the Angel continued to give the Prophet (blessings of Allah be upon him and his family) an explanation on the greatness of this supplication, which we will omit from here due lo lack to space. However it suffices us to state that whoever reads this supplication with a pure intention in the BEGINNING of the month of Ramadhan, Allah (Glory and Greatness be to Him) will grant him sustenance on the Night of Power and will create for this person 70,000 Angels who will all be busy in the praising and glorification of Allah (Glory and Greatness be to Him) and will give this reward to the person who has read this supplication.
With this said, we see the greatness of the recitation of this supplication.
In addition, it is mentioned that whoever reads this supplication three times during the month of Ramadhan, Allah (Glory and Greatness be to Him) will make the hell-fire forbidden on him and would make it obligatory for that person to go into Paradise.
For such a person, Allah (Glory and Greatness be to Him) will also appoint two Angels to protect that person from all evils (in this world) and he would be in the protection of Allah (Glory and Greatness be to Him) for as long as he is alive.
In the final Hadith of this supplication, it has been narrated from Imam Hussein ibn 'Ali (prayers be upon him) that, "My father Amir al-Mo 'minin 'All ibn Abi Talib (prayers be upon him) had bequeathed to me that I should memorize and protect this supplication and write it on the Kafan (burial shroud) and that I should teach it to my family members and he highly encouraged me to read this supplication as it contains 1,000 names of Allah and within these names is the Greatest Name of Allah (Isme- e –A’dham)."
The late Shaykh `Abbas al-Qummi (Compiler of the book Mafatih al-Janan) states that, “From this Hadith, we can derive the following points that first off, it is recommended to write this supplication on one’s kafan just as the late scholar `Allamah Bahrul `Ulum (may Allah grant him peace) has hinted to in a poem:
• And it is recommended to write on the Kafan of the Deceased
• The testimony of Islam and Iman
• And also, the writing of the Quran,
• And the (supplication) of Joshan as it is a protection from the fire of hell.
The second point we can deduce from the Hadith is that it is recommended to recite this supplication in the BEGINNING of the month of Ramadhan and there are no ahadith that tell us to recite this supplication on the specific Nights of Power (Laylatul-Qadr). However, `Allamah Majlisi (may Allah raise his rank), in his book, Zadul Maad, under the various acts that should be performed on the Night of Power (Laylatul-Qadr) has stated that in some Hadith, it has been mentioned to read this supplication on one of the three nights of Power. Thus, his words are sufficient for us (May Allah grant him a resting place in the Adobe of Peace).
This supplication has 100 sections and each section contains 10 names of Allah (Glory and Greatness be to Him) and at the end of each section this line should be repeated:
Praise be to Thee, there is no god but Thee, The Granter of all Succor, Protect us from the Fire, O Lord