"And a Qur'an We have divided/separated, that you might recite it to the people at intervals," meaning: over a long duration. As for the one who read it with the light form (faragna-hu), the meaning is: He distinguished within it between truth and falsehood, and between the lawful and the prohibited. And the one who read it with the heavy form (farraqna-hu), the meaning is: Allah separated it; so He sent it down day after day, month after month, and year after year, in stages, for your heart to be settled by it.
Muhammad said: His word "a Qur'an" is in the accusative case due to an implied verb; the meaning is: And We have divided it as a Qur'an.
﴿وقرآنا فَرَقْنَاهُ لِتَقْرَأَهُ عَلَى النَّاسِ عَلَى مكث﴾ أَيْ: طُوْلٍ، وَمَنْ قَرَأَهَا بِالتَّخْفِيفِ، فَالْمَعْنَى: فَرَقَ فِيهِ بَيْنَ الْحَقِّ وَالْبَاطِلِ، وَالْحَلَالِ وَالْحَرَامِ، وَمِنْ قَرَأَهَا بِالتَّثْقِيلِ، فَالْمَعْنَى: فَرَّقَهُ اللَّهُ؛ فَأَنْزَلَهُ يَوْمًا بَعْدَ يَوْمَ، وَشَهْرًا بَعْدَ شَهْرٍ، وَعَامًا بَعْدَ عَامٍ مُنَجَّمًا يَقَرُّ بِهِ قَلْبُكَ.
قَالَ مُحَمَّدٌ: قَوْله (قُرْآنًا) مَنْصُوبٌ بِفِعْلٍ مُضْمَرٍ؛ الْمَعْنَى: وَفَرَقْنَاهُ قُرْآنًا. (ل ١٩١)
