"[A reward from your Lord, a gift [that is] calculated (Jaza'an min rabbika 'ata'an hisaban)]": Mujahid's interpretation means: according to the measure of their deeds; this is because they are given stations according to the measure of their deeds, then they are provided sustenance therein without measure.
﴿جَزَاءً مِنْ رَبِّكَ عَطَاءً حِسَابًا﴾ تَفْسِيرُ مُجَاهِدٍ: يَعْنِي: عَلَى قَدْرِ أَعْمَالِهِمْ؛ وَذَلِكَ أَنَّهُمْ يُعْطَوْنَ الْمَنَازِلَ عَلَى قَدْرِ أَعْمَالِهِمْ، ثُمَّ يُرْزَقُونَ فِيهَا بِغَيْرِ حِسَابٍ
