﴿ وَأَنَّ عَذَابِى هُوَ ٱلْعَذَابُ ٱلْأَلِيمُ ﴾

“and [also,] that the suffering which I shall impose [on sinners] will indeed be a suffering most grievous.”

(And that My doom is the dolorous doom) the painful doom for the one who does not repent and dies in a state of disbelief.