In The Name of Allah, The Beneficent, The Merciful
No. 83 (36 Verses)
Contents of the Sura:
Opinions are divided about this Sura on whether it is a Meccan Sura or a Medinan one.
One of the occasions of revelation of the Sura denotes that the beginning verses of the Sura, which are about shortchanging, can be about those tradesmen who dealt in fraud in Medina.
Other verses of the Sura mostly resemble, from the point of tone, the Meccan Suras, whose short and meaningful verses warn of the Resurrection and the horrible events of the Hereafter. Particularly, the last verses of the Sura, which speak about the mockings of the disbelievers at the believers, match the earlier environment of Mecca where Muslims were in a minority and unbelievers were in a majority.
Perhaps, it is for this reason that some commentators consider a part of the Sura Meccan and another part of it belonging to the Medina period. But, on the whole, this Sura seems chronologically close to the Meccan period.
In any case, the theme of the Sura is divided into five categories:
1. It seriously warns and threatens the defrauders.
2. It points to the lack of strong belief in the Resurrection as being the origin of corruption and great sins.
3. There are some hints in this Sura showing the end of the Wicked on That Great Day.
4. It points to some of the great gifts and delightful blessings of the Righteous in the Garden of Bliss.
5. The unbelievers, foolishly mocking at the believers, in this life, and the reverse situation, in the Hereafter is briefly referred to in the Sura.
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The Virtue in Studying the Sura:
There is a tradition from the holy Prophet (p.b.u.h) that says: "The person who studies Sura Mutaffifin (Defrauders), Allah will make him drink of the pure, sealed drink on That Day 8." 
And there is also a narration from Imam Sadiq (p.b.u.h.) which says: "The person who recites Sura Mutaffffin (Defrauders) in his obligatory prayers, Allah will keep him safe from fire on the Day of Judgement. Then, neither the fire will meet him nor will he meet the fire." 
These great rewards are for the one who studies it and acts
accordingly, of course.
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 Majma'-al-Bayan, vol. 10, p. 451.
 Thawab-ul-a'mal, based on
Nur-uth-Thaqalayn, vol. 5, p. 527.