Muhammad 47:18

Fahal yanthuroona illaassaAAata an ta/tiyahum baghtatan faqad jaaashratuha faanna lahum itha jaat-humthikrahum

Then do they await except that the Hour should come upon them unexpectedly? But already there have come [some of] its indications. Then how [i.e., what good] to them, when it has come, will be their remembrance?

They are waiting for nothing but for the Hour (of Doom) that it should come upon them suddenly. So, its signs have already come. Then, once it will come upon them, how would they have an opportunity to accept the advice (already) given to them?