Surah 15. Al-Hijr, Ayah 63

Lit., "that about which they have persistently been (kanu) in doubt" - i.e., the doom which, in this world or in the hereafter, is the inevitable consequence of deliberate sinning: a prediction which the sinners themselves so often deride (cf. {6:57-58}, 8:32 , 11:8 , and the corresponding notes). To my mind, this sentence constitutes the reason for the repetition, in this surah, of the stories of Lot's people and the other sinful communities of old that were punished for their persistent transgressions against all moral laws.

The unusual appearance of the angels struck Lot as it had struck Abraham. Knowing the abominable vices to which the Cities were addicted, he feared to entertain handsome young men. They at once disclosed their mission to him. In effect they said: "You, Lot, have been preaching in vain to these wicked Cities. When you warn them of their inevitable end: Destruction, they laugh and doubt. Now their doubt will be resolved. Their destruction will be accomplished before the morning."