Surah 40. Ghafir, Ayah 49

I.e., the angelic forces that are to watch over the suffering of the sinners in the hereafter: perhaps an allegory of the belated awakening of the latters' conscience.

 The verse does not say “Those in the Fire will cry out to its keepers,” simply because there are levels in the Fire: those in higher levels will plead to the keepers of the depths of Hell to appeal to Allah to lighten the punishment even for one day, since they think they are better than those at the bottom.

Cf. xxxix. 71. The poor misguided ones will turn to the angels who are their Keepers, asking them to pray and intercede for them. But the angels are set there to watch over them, not to intercede for them. In their innocence they ask, 'Did you have no warnings from messengers, men like yourselves, in your past life?'