وَهُوَ الْقَاهِرُ فَوْقَ عِبَادِهِ
He is the Qahir over His servants.
The Qahir means, the one who controls everything, all are subservient to His supreme grace, greatness and majesty,
وَيُرْسِلُ عَلَيْكُم حَفَظَةً
and He sends guardians over you,
angels who guard mankind.
In another Ayah, Allah said;
لَهُ مُعَقِّبَـتٌ مِّن بَيْنِ يَدَيْهِ وَمِنْ خَلْفِهِ يَحْفَظُونَهُ مِنْ أَمْرِ اللَّهِ
For each (person), there are angels in succession, before and behind him. They guard him by the command of Allah. (13;11),
watching his deeds and recording them.
Allah said,
وَإِنَّ عَلَيْكُمْ لَحَـفِظِينَ
But verily, over you (are appointed angels in charge of mankind) to watch you. (82;10)
and,
إِذْ يَتَلَقَّى الْمُتَلَقِّيَانِ عَنِ الْيَمِينِ وَعَنِ الشِّمَالِ قَعِيدٌ
مَّا يَلْفِظُ مِن قَوْلٍ إِلاَّ لَدَيْهِ رَقِيبٌ عَتِيدٌ
(Remember!) that the two receivers (recording angels) receive, one sitting on the right and one on the left. Not a word does he utter, but there is a watcher by him, ready. (50;17-18)
Allah's statement,
حَتَّىَ إِذَا جَاء أَحَدَكُمُ الْمَوْتُ
until when death approaches one of you...
refers to, when one's life span comes to an end and he is dying,
تَوَفَّتْهُ رُسُلُنَا
Our messengers take his soul...
meaning, there are angels who are responsible for this job.
Ibn Abbas and several others said that;
the Angel of Death has angels who pull the soul from its body and when it reaches the throat, the Angel of Death captures it.
Allah said;
وَهُمْ لَا يُفَرِّطُونَ
and they never neglect their duty.
They guard the soul of the dead person and take it to wherever Allah wills, to Illiyyin if he was among the righteous, and to Sijjin if he was among the wicked (disbelievers, sinners, etc.), we seek refuge with Allah from this end.
Allah said next