What is the Islamic position with respect to bringing back the spirits of the dead? When one studies the texts related to this point, he will conclude with certainty that such an act is absolutely impossible. Allah سبحانه و تعالى has informed us that the spirit is from the unseen which man cannot possibly fathom or reach.
The Prophet صلى الله عليه وسلم has made clear to us how the angel of death takes the soul at the time of death and what happens to it after that. If the souls are held by Allah سبحانه و تعالى and in the charge of strong guardians, it is not possible that they escape from them and come to the people and talk to them and play with the minds of humans.
Some of the mediums claim that the spirit of some righteous person, martyr or prophet has come to them. How could it be that they would leave the bounties of paradise to come to this world to come to the dark rooms of the mediums? Allah سبحانه و تعالى has informed us that the martyrs are alive with their Lord. The Prophet صلى الله عليه وسلم has informed us that the souls of the martyrs are in green birds in paradise; they eat from the fruits of paradise and drink from its streams. And they are hanging from the Throne of the Lord. How do these liars of today claim that spirits are appearing before them? This is a grave sin that comes from their mouths and they say nothing but a lie.
A Conjecture and a Reply
Some people may ask, "How is it that these spirits know the deeds and the character of the persons who they claim to be?"
The one who claims that he is a spirit is actually a devil jinn. Perhaps that devil jinn is the partner that accompanied that human through his life. Every human has a devil jinn who accompanies him. That devil jinn accompanies him and knows many aspects related to his character, habits, attributes, friends, relatives and so forth. 
It is very easy for them to answer the questions put to them because they have such knowledge. 
 A séance is an attempt to communicate with spirits. The word "séance" comes from the French word for "seat," "session" or "sitting," from the Old French "seoir," "to sit." In French, the word's meaning is quite general: one may, for example, speak of "une séance de cinéma" ("a movie session"). In English, however, the word came to be used specifically for a meeting of people who are gathered to receive messages from spirits or to listen to a spirit medium discourse with or relay messages from spirits; many people, including skeptics and non-believers, treat it as a form of entertainment. In modern English usage, participants need not be seated while engaged in a séance.
 The Prophet صلى الله عليه وسلم said: “There is none of you who does not have a companion (qareen) appointed for him from among the jinn.” They said, “Even you?” He said, “Even me, but Allah helped me against him fa aslama [or fa aslamu], so he only tells me to do that which is good.” (Saheeh Muslim)
There are two well-known views that have been reported. Those who read the phrase as fa aslamu said that it means, “So I am safe [aslamu] from his evil and temptation.” Those who read it as fa aslama said that it means, “The qareen became Muslim [aslama] and became a believer, so he only tells me to do that which is good.”
They differed as to which view is correct. Al-Khattabi رحمه الله said: The correct version is fa aslamu [so I am safe]. Al-Qadi ‘Iyad رحمه الله thought that fa aslama [so he became Muslim] was correct, and this is the preferred version, because he then said, “so he only tells me to do that which is good.” And they differed concerning the report that says fa aslama. It was said that it means he submitted in the sense of surrendering, and it appears in this form (fa astaslama – so he surrendered) in reports narrated elsewhere than in Saheeh Muslim. And it was said that it means that he became a Muslim and a believer. This is the apparent meaning.
Abu Na’eem al-Asbahani رحمه الله said in Dalail al-Nubuwwah: It was said aslama meaning he believed. The Prophet صلى الله عليه وسلم was the only one whose qareen became a Muslim and a believer.
Based on this, having one’s qareen become a Muslim was something that was unique to the Prophet (peace and blessings of Allah be upon him).
 Shaykh Sulayman al-Ashqar رحمه الله: The World of the Jinn and Devils