Аль-Вакиа 56:85

When the Soul reaches the Throat at the Time of Death, it cannot be brought back; this proves Reckon

Allah the Exalted said,

(Then why do you not (intervene) when it reaches), in reference to the soul,

(Al-Hulqum), i.e., the throat, at the time of death. Allah the Exalted said in other Ayat,

(Nay, when (the soul) reaches to the collar bone, and it will be said: "Who can cure him (and save him from death)" And he will conclude that it was (the time) of parting (death); And one leg will be joined with another leg (shrouded). The drive will be on that Day to your Lord (Allah).)(75:26-30) Allah said here,

(And you at the moment are looking,) at the dying person and witnessing the stupor of death that he is experiencing,

(But We are nearer to him than you, ) with Our angels,

(but you see not.) you cannot see the angels. Allah the Exalted said in another Ayah,

(He is the Irresistible over His servants, and He sends guardians (angels) over you, until when death approaches one of you, Our messengers (angel of death and his assistants) take his soul, and they never neglect their duty. Then they are returned to Allah, their true Protector. Surely, for Him is the judgement and He is the swiftest in taking account.)(6:61-62) Allah's statement,

(Then why do you not -- if you are not Madinin -- return the soul,) means, `Will you not return this soul, that has reached the throat, to its body as it used to be, if you are exempt from the reckoning and recompense' Sa`id bin Jubayr and Al-Hasan Al-Basri said:

(Then why do you not -- if you are not Madinin. ..), "If you do not believe that you will be reckoned, recompensed, resurrected and punished, then why do you not return this soul to its body" Mujahid said that,

(...if you are not Madinin), means, "if you are not certain."