﴿ وَجَآءَتْ سَكْرَةُ ٱلْمَوْتِ بِٱلْحَقِّ ۖ ذَٰلِكَ مَا كُنتَ مِنْهُ تَحِيدُ ﴾

“And [then,] the twilight of death brings with it the [full] truth that [very thing, O man,] from which thou wouldst always look away! –”

And the agony of death its throes and distress arrives with the truth of the Hereafter such that the one who denied it sees it with his own eyes — and this is the distress itself. That namely death is what you used to shun what you used to flee from and be terrified by.