We have made only angels as the keepers of the fire (for they are the strongest in carrying out Our commands). Our informing (people) of the numbers of these angels is a trial for the disbelievers. It gives more certainty to the people of the Book and strengthens the faith of the believers. The people of the Book and the believers have no doubt about it. We have fixed the number to make the disbelievers and those whose hearts are sick say, "What does God mean by such a parable?" Thus, God guides and causes to go astray whomever He wants. No one knows about the army of your Lord except He Himself. This parable is a reminder for mankind.