"So set your face," meaning your orientation, "toward the upright religion," which is Islam, "before there comes a Day from Allah which cannot be averted," meaning the Day of Resurrection. "On that Day they will be divided," meaning they will split into groups: one group in Paradise and one group in the Blazing Fire.
﴿فأقم وَجهك﴾ أَي: وجهتك ﴿للدّين الْقيم﴾ الْإِسْلَامِ ﴿مِنْ قَبْلِ أَنْ يَأْتِيَ يَوْمٌ لَا مَرَدَّ لَهُ مِنَ الله﴾ يَعْنِي: يَوْمَ الْقِيَامَةِ ﴿يَوْمَئِذٍ يَصَّدَّعُونَ﴾ يَتَصَدَّعُونَ؛ أَيْ: يَتَفَرَّقُونَ: فَرِيقٌ فِي الْجنَّة وفريق فِي السعير
