"And We have not made the keepers of the Fire except as angels"—that is: who can withstand them? "And We have not made their number except as a trial"—meaning a tribulation—"for those who disbelieve, so that those who were given the Scripture may be certain"—because they find them in their books to be nineteen—"and that those who have believed may increase in faith"—in confirmation—"and that they may not doubt"—meaning: waver in skepticism.
﴿وَمَا جَعَلْنَا أَصْحَابَ النَّارِ إِلا مَلَائِكَة﴾ أَيْ: فَمَنْ يُطِيقُهُمْ؟ ﴿وَمَا جَعَلْنَا عدتهمْ إِلَّا فتْنَة﴾ بليَّة ﴿لِلَّذِينَ كَفَرُوا لِيَسْتَيْقِنَ الَّذِينَ أُوتُوا كتاب﴾ لِأَنَّهُمْ فِي كُتُبُهِمِ تِسْعَةَ عَشَرَ ﴿ويزداد الَّذين آمنُوا إِيمَانًا﴾ تَصْدِيقًا ﴿وَلَا يرتاب﴾ يَشُكُّ
