70. The subsequent sentence shows that this is the answer to a question which was frequently put to the Prophet (peace be upon him) by the disbelievers of Makkah. The question which has not been cited was this: If the Resurrection so often you talk of is really coming, let us know the date of its coming.
71. That is, don’t be under the delusion that the Resurrection will come gradually and take a long time: you will neither be able to see it coming at a distance nor guard against it and make preparations to meet it. For it will come suddenly without any previous notice, in the twinkling of an eye or even will take less time than this. Therefore, now is the time to consider this matter seriously and to decide about your attitude towards it. You should not depend upon this false hope that there is still a long time in the coming of the Resurrection and you will set matters right with Allah when you will see it coming.
It may be pointed out that the Resurrection has been mentioned here during the discussion on Tauhid in order to warn the people that the choice between the doctrines of Tauhid and shirk is not merely a theoretical question. For that choice determines different courses of life for which they will be called to account on the Day of Resurrection. They have also been warned that it will come all of a sudden at some unknown time. Therefore, they should be very careful to make that choice which will determine their success or failure on that Day.