Al-Hajj 22:55

Wala yazalu allatheenakafaroo fee miryatin minhu hatta ta/tiyahumu assaAAatubaghtatan aw ya/tiyahum AAathabu yawmin AAaqeem

But those who disbelieve will not cease to be in doubt of it until the Hour comes upon them unexpectedly or there comes to them the punishment of a barren Day.

Those who disbelieve will remain in doubt about it (the Qur’ān) forever, until the Hour (of Judgment) comes upon them suddenly, or there comes to them the punishment of a barren day.