وَأَنذِرهُم يَومَ الحَسرَةِ إِذ قُضِيَ الأَمرُ وَهُم في غَفلَةٍ وَهُم لا يُؤمِنونَ

And warn them, [O Muhammad], of the Day of Regret, when the matter will be concluded; and [yet], they are in [a state of] heedlessness, and they do not believe.