﴿31﴾ وَمَا جَعَلْنَا أَصْحَابَ النَّارِ إِلَّا مَلاَئِكَةً وَمَا جَعَلْنَا
on the point: "We have set none but angels as guardians of the Fire." Such angels are so powerful and in the Qur’anic terms ghalāz and shidād, i.e. stern and strict, that all sinners shall be feeble and week before them.
The blessed Verse proceeds to say "We have fixed their number only as a trial for the disbelievers." The trial aimed at two things: firstly, they derived the number nineteen, whereas any other number could engender the same question. Secondly, they regarded the number nineteen to be few and said derisively that they could appoint ten people against each of them and thereby overcome them. They were unaware of the truth that the angels are so powerful that according to the Holy Qur’an, a number of them sufficed to send the people of Lot (as) to perdition by totally destroying their prosperous cities. Further, the preceding blessed Verses treated of the points lying behind the number of the guardians of Hell; however, the blessed Verse in question adds: "So that the people of the Book may arrive at a certainty." In this respect, it is narrated that the Noble Prophet (SAW) was asked by his companions regarding the number of the guardians of Hell. He replied: "Allah and His Messenger (SAW) know better." Gabriel was sent down and revealed unto him that they were nineteen angels appointed as the guardians of Hell.
The people of the Book did not protest against the number which reflects that they had found the number in line with their Scriptures. Thus, they arrived at further certitude as to the Prophetic Call of Allah’s Messenger (SAW). Besides, the believers’ faith was further firmly established. Thus, the blessed Verse proceeds to say: "[the aim was] that the believers may increase their faith." Further emphasis is laid on the three goals: the faith of the people of the Book, that of the believers in the Islamic faith, and the trial of the polytheists and disbelievers: " that no doubt may be left for
 Tafsīr Marāghī, vol. 29, p. 134.
the people of the Book and the believers; further [the number nineteen made] those in whose hearts is a disease and the disbelievers may say: 'What Allah intends by this example?" Regarding "those in whose hearts is a disease," some Qur’an exegetes hold that the hypocrites are hereby intended, since the Qur’anic expression alludes to them, an instance of which is "In their hearts is a disease and Allah has increased their disease" (2:10). Nonetheless, further investigation of the Qur’anic instances of the expression reflects that it does not solely include the hypocrites, but it encompasses all the disbelievers who take a belligerent stance against the Qur’anic Verses.
The blessed Verse further says: "Thus, Allah leads astray whom He wills and guides whom He wills. And none may know the hosts of your Lord but He." The aforesaid remarks clearly reflect that Divine Will as to guiding some people and leading some others astray is well-measured. Those who are in error deserve no better than that and those obedient to Allah deserve such Guidance. In other words, God Almighty does not intend to harm some people by leading them astray, but error is the disbelievers’ chastisement. Put the case that a thief breaks into your home and you lock the doors. Confining him does not entail leading him astray, but it aims at chastising him. What should be borne in mind regarding God Almighty leading some people astray, as reflected in a number of the Qur’anic Verses, that the Arabic word idlāl denotes abandoning someone, implying that God Almighty abandons those who do not deserve to be guided; the similitude of which is a farmer who abandons the rotten seeds but keeps the good ones and paves the ground for their growth.
The closing clauses of the blessed Verse read: "And none may know the hosts of your Lord but He. And this is nothing else than a reminder to mankind." The nineteen guardians of Hell does not reflect the total number of the
hosts of the Lord, but the number of the latter are so large that according to some of the traditions, the earth and the heaven are filled with them, such that there is no spot in the entire world of existence unless there is an angel glorifying God Almighty there. For further details in this respect, one may refer to elevated words of Imam ‘Alī as recorded in the first sermon of the Nahj al-Balāgha.
Different suggestions have been made by Qur’an exegetes concerning the antecedent of the pronoun hiya ("this, it") in wa mā hiya illā dhikrā li-’l-bashar ("And this is nothing else than a reminder to mankind." Some maintain that the hosts of the Lord some of whom are the guardians of Hell are the antecedent. Some hold that saqar ("Hell") is the antecedent. There are some exegetes who believe that reference is made to the Holy Qur’an. Although they all lead to awakening, reminder, and awareness, but the first suggestion is more in line with the tone of the Verse, since the aim is to state the truth that if God Almighty has selected hosts, it does not reflect that He cannot chastise all the enemies and sinners Himself, but they all serve as a reminder, awakening, and according attention to the seriousness of Divine torment.