We have appointed only angels to be wardens of the Fire, and their number have We made to be a stumbling-block for those who disbelieve; that those to whom the Scripture hath been given may have certainty, and that believers may increase in faith; and that those to whom the Scripture hath been given and believers may not doubt; and that those in whose hearts there is disease, and disbelievers, may say: What meaneth Allah by this similitude? Thus Allah sendeth astray whom He will, and whom He will He guideth. None knoweth the hosts of thy Lord save Him. This is naught else than a Reminder unto mortals.