"How, then, will it be when We assemble them for a Day about which there is no doubt?" meaning: no uncertainty regarding it.
Muhammad said: The meaning—and Allah knows best—is: How will their state be on that Day? This is a form of conciseness. "And every soul will be paid in full for what it has earned." As for the believer, he will be paid in full for his good deeds in the Hereafter; and as for the disbeliever, he is recompensed for them in this world, and he shall have the punishment of the Fire in the Hereafter. [Verse 26]
﴿فَكَيْفَ إِذَا جَمَعْنَاهُمْ لِيَوْمٍ لَا ريب فِيهِ﴾ لَا شكّ فِيهِ.
قَالَ مُحَمَّد: الْمَعْنى - وَالله أعلم - فَكيف يكون حَالهم فِي ذَلِكَ الْيَوْم؛ وَهَذَا من الِاخْتِصَار. ﴿وَوُفِّيَتْ كُلُّ نَفْسٍ مَا كسبت﴾ أما الْمُؤْمن فيوفى حَسَنَاته فِي الْآخِرَة، وَأما الْكَافِر فيجازى بِهَا فِي الدُّنيا، ولَهُ فِي الْآخِرَة عَذَاب النَّار. [آيَة ٢٦]
