Taha 20:15

Inna assaAAata atiyatunakadu okhfeeha litujza kullu nafsin bimatasAAa

Indeed, the Hour is coming - I almost conceal it - so that every soul may be recompensed according to that for which it strives.

Surely, the Hour (i.e. the Day of Judgment) has to come. I would keep it secret, so that everyone is given a return for the effort one makes.