And whoever does an atom’s weight of evil will see it (8).” [al-Zalzalah: 7–8].

Since belief in the Last Day and in the reward and punishment it entails is one of the tenets that must be affirmed, and since a person’s sights may extend no further than this worldly life and its pleasures—causing him to forget the Last Day and fail to prepare for it—Allah placed signs before the Hour that attest to its reality and show that it will inevitably occur, so that not the slightest doubt about it enters people’s minds and nothing beguiles them away from it.

It is well known that whenever the truthful one, whose truthfulness is attested—may Allah bless him and grant him peace—mentions one of its signs and people see that sign come to pass, they know with certainty that the Hour is coming, beyond all doubt. They will therefore work in preparation for it, ready themselves for that Day, and provision themselves with righteous deeds before it is too late and their appointed term expires:

“Lest a soul should say, ‘Alas for me, for having neglected my duty to Allah and having been among the mockers!’ (56) Or should say, ‘If only Allah had guided me, I would have been among the righteous.’ (57) Or should say, upon seeing the punishment, ‘If only I could return, I would be among those who do good.’” [al-Zumar: 56–58].

The Prophet—may Allah bless him and grant him peace—would say in his sermon, “The Hour and I were sent like these two.”

Whenever he mentioned the Hour, his cheeks would redden, his voice would rise, and his anger would intensify, as though he were warning of an attacking army and saying, “The enemy is upon you at dawn! The enemy is upon you at dusk!” (1).