﴿ وَلَتَعْلَمُنَّ نَبَأَهُۥ بَعْدَ حِينٍۭ ﴾

“and you will most certainly grasp its purport after a lapse of time!””

(And ye will come in time to know the Truth thereof) you will know the Truth of the Qur'an and that which it contains of promises and threats after you believe; and it is also said: after death. Some came to know after they accepted faith: these are the believers; and some came to know after death and these are the disbelievers. Both came to know that what Allah said in the Qur'an is the Truth'.