Al-Muddaththir 74:31 وما جعلنا اصحاب النار الا ملايكة وما جعلنا عدتهم الا فتنة للذين كفروا ليستيقن الذين اوتوا الكتاب ويزداد الذين امنوا ايمانا ولا يرتاب الذين اوتوا الكتاب والمومنون وليقول الذين في قلوبهم مرض والكافرون ماذا اراد الله بهاذا مثلا كذالك يضل الله من يشاء ويهدي من يشاء وما يعلم جنود ربك الا هو وما هي الا ذكرى للبشر ٣١

And We have set none but angels as guardians of the Fire. And We have fixed their number (19) only as a trial for the disbelievers, in order that the people of the Scripture (Jews and Christians) may arrive at a certainty [that this Qur’ân is the truth as it agrees with their Books regarding the number (19) which is written in the Taurât (Torah) and the Injeel (Gospel)] and that the believers may increase in Faith (as this Qur’ân is the truth), and that no doubt may be left for the people of the Scripture and the believers, and that those in whose hearts is a disease (of hypocrisy) and the disbelievers may say: "What Allâh intends by this (curious) example ?" Thus Allâh leads astray whom He wills and guides whom He wills. And none can know the hosts of your Lord but He. And this (Hell) is nothing else than a (warning) reminder to mankind.