الآية رقم (4) - كَلَّا سَيَعْلَمُونَ

(4) - (No! They are going to know. (4))

كَلَّا (No) : This word is used as a rebuke and forbiddance.

سَيَعْلَمُونَ : The letter (Sin) affixed to the verb is used to indicate the future. They are going to know what will happen to them as they denied the resurrection.