ثُمَّ كَلَّا سَيَعْلَمُونَ
No!, again, they will come to know!
The difference between this verse and the previous one is one word ثُمَّ
So the question, why has the same sentence (minus ثُمَّ) been mentioned twice. There are two views. 1) It is a repetition which conveys a sense of emphasis. 2) There are two predominate things that the Quran warns about: the Resurrection and Hell. It is believed they will 1st know the truth at two separate times: 1st the Resurrection and the 2nd when they see Hell.
Allah says they will know but He does not tell them what they will come to know. The listener is expecting to be told what they will know, however, Allah again repeats what they will come to know. This is creating a type of suspense and a type of sensational feelings within the one who hears these verses.
The thing they will come to know has been omitted to make it expansive and comprehensive. This shows they will come to know a lot. The punishment in the grave, the Resurrection, HELL etc so by leaving out what they will come to know it is not restricted to one thing i.e Resurrection.
Another reason for omitting what they will come to know is to tell the listener that you will see it, only then will you come to know. And by seeing it (this punishment) necessitates that will feel it (this punishment). Explain wont do justice to what they will experience.
ContemplateQuran 