بَلْ قُلُوبُهُمْ فِي غَمْرَةٍ
...
Nay, but their hearts are covered,
meaning because of negligence and misguidance,
...
مِّنْ هَذَا
...
from this.
means, the Qur'an which Allah revealed to His Messenger.
...
وَلَهُمْ أَعْمَالٌ مِن دُونِ ذَلِكَ هُمْ لَهَا عَامِلُونَ
and they have other deeds, besides which they are doing.
Al-Hakam bin Aban narrated from Ikrimah, from Ibn Abbas that;
وَلَهُمْ أَعْمَالٌ
(and they have other deeds),
means, evil deeds apart from that, i.e., Shirk,
هُمْ لَهَا عَامِلُونَ
(which they are doing),
means, which they will inevitably do.
This was also narrated from Mujahid, Al-Hasan and others.
Others said that this phrase
وَلَهُمْ أَعْمَالٌ مِن دُونِ ذَلِكَ هُمْ لَهَا عَامِلُونَ
(And they have other deeds, besides which they are doing), means:
It was decreed that they would do evil deeds, and they will inevitably do them before they die, so that the word of punishment may be justified against them.
A similar view was narrated from Muqatil bin Hayyan, As-Suddi and Abdur-Rahman bin Zayd bin Aslam.
This is a clear and appropriate meaning. We have already quoted from the Hadith of Ibn Mas`ud:
فَوَ الَّذِي لاَ إِلهَ غَيْرُهُ إِنَّ الرَّجُلَ لَيَعْمَلُ بِعَمَلِ أَهْلِ الْجَنَّةِ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَهَا إِلاَّ ذِرَاعٌ فَيَسْبِقُ عَلَيْهِ الْكِتَابُ فَيَعْمَلُ بِعَمَلِ أَهْلِ النَّارِ فَيَدْخُلُهَا
By Him besides Whom there is no other God, a man may do the deeds of the people of Paradise until there is no more than a forearm's length between him and it, then the decree will overtake him and he will do the deeds of the people of Hell, then he will enter Hell...
حَتَّى إِذَا أَخَذْنَا مُتْرَفِيهِم بِالْعَذَابِ إِذَا هُمْ يَجْأَرُونَ