Commentary
وَمَن يَعْشُ عَن ذِكْرِ الرَّحْمَـٰنِ (And whoever makes himself blind against the advice of the Rahman, We assign for him a devil who accompanies him all the time - 43:36) It means that whoever knowingly turns a blind eye towards Allah's advice i.e. the Holy Qur'an and wahy, Allah assigns to him a devil who accompanies him all the time in this world to prevent him from virtuous deeds, and to divert him towards evil. When such a man is resurrected in the Hereafter, his devil will also be with him, till they both are pushed in Hell. (Qurtubi).
We learn from this that the punishment one gets even in this world for turning away from Allah's remembrance is that he gets into bad company and 'shaitans' (devils), whether from humans or from jinns, keep diverting him from virtues to vices. He commits vices but thinks that he is doing very well. (Qurtubi). This devil who is assigned to such a person, as mentioned here, is in addition to the 'Shaitan' (Satan) who is attached to every believer and disbeliever, because that 'shaitan' (Shaitan) does leave the man alone at certain specific times, whereas this devil accompanies him all the time. (Bayan-ul-Qur an)