"Nay, you shall come to know. Then, nay, you shall come to know." This is a warning followed by another warning.
﴿كَلَّا سَوْفَ تَعْلَمُونَ ثُمَّ كَلَّا سَوف تعلمُونَ﴾ وَهَذَا وعيداً بعد وَعِيد
