How are the Jinn able to tell secrets or speak in a deceased person’s voice?

The jinn may be divided into two categories according to their faith: Muslim (believers) and Kafir (disbelievers).The disbelievers among the Jinn are referred to by various names in both Arabic and English: ‘Ifreet, Shayran, Qareen, demons, devils, spirit, ghosts etc. They try to misguide man in various ways. Whoever listens to them becomes a worker for them and is referred to as a human Shaytan (devil). Allah says in;

“And thus We have made for every prophet an enemy - devils from mankind and jinn, inspiring to one another decorative speech in delusion. But if your Lord had willed, they would not have done it, so leave them and that which they invent.”[1]

Every human has an individual Jinn accompanying him, referred to as a Qareen (i.e. companion). This is a part of man’s test in this life. The Jinn encourages his lower desires and constantly tries to divert him from righteousness.

Allaah says in (interpretation of the meaning);

“His [devil] companion will say; ‘Our Lord! I did not make him transgress [in disbelief, oppression, and evil deeds], but he was [himself] was in extreme error.’

[Allaah] will say: ‘Do not dispute before Me, while I had already presented to you the threat [I.e., warning].

The word [i.e., decree] will not be changed with Me, and I am not unjust to the servants’”[2]

The Prophet (ﷺ) referred to this relationship as follows:

“Every one of you has been assigned a companion from the Jinn.” The Sahabah asked, “Even you, O’ Messenger of Allah (ﷺ)?” and the Prophet (ﷺ) replied, “Even me, except that Allah has helped me against him and he has submitted; now he only tells me to do good.”[3]

The norm for the people is that this evil jinn provides the evil whispering and evil suggestion, which is one of the sources through which evil comes to us.

As each person is accompanied by a jinni, he is also accompanied by an angel who inspires him and helps him to do righteous deeds. So this is the struggle which each soul faces and it is part of the test of this life. The evil Jinn may aid their partners in sin and disbelief in Allah. Their goal is to draw as many others as they can into the gravest of sins, the worship of others besides or along with Allah. So, that is the negative source that comes to us, and this might be the cause of people who are involved in medium shirk; where a person goes to somebody that can supposedly channel the spirit of his dead father or grandfather. This person speaks either in the voice of that person, or they speak about things which only he and that person knew. So, it has been suggested that this would be from Qareen because he doesn’t die when the person dies. The Qareen, remains in the world among the jinns and those involved in this type of medium shirk, and may transmit themselves into trances and whatever opens them up for that type of possession.

‘Abd-Allaahibn al-Imaam Ahmad said: “I told my father that some people claim that the jinn do not enter the body of a human. He said, ‘O my son, they are lying, for a jinn may speak with the tongue of a person who is lying on his sick-bed.’” [4]

References:

[1] Surah Al-An’aam, 6:112

[2] Surah Qaf, 50:27-29

[3] Muslim (Eng. Translation), Vol 4, p.1472, Hadith: 6757

[4] Shaykh al-Islam IbnTaymiyah, Majmoo’ Fataawa, 19/12