I know that the devil can only influence man through whisperings, but is it possible for a Jinn to appear to a person in a form that may harm him? I feel that the devil whispers to me and tries to frighten me of the possibility of seeing a Jinn. What should I do?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

The existence of Jinns is a fact, and Allaah The Almighty has informed us of this in the Quranic verse where He Says (what means): {And I did not create the Jinn and mankind except to worship Me.} [Quran 51:56]

Allaah The Almighty also Says that Jinns see humans from where humans cannot see them. Indeed Allaah The Almighty Says (what means): {Indeed, he sees you, he and his tribe, from where you do not see them.} [Quran 7:27]

This verse means that the Jinns see humans in a way that humans cannot see. However, this does not mean that it is impossible for a human to see a Jinn; rather people may see them but not in all states, that is, the Jinn may appear in different forms and shapes.

Allaah The Almighty also Says that Jinns plot against humans, yet He judges their plotting to be weak.  Allaah The Almighty Says (what means): {The plot of Satan has ever been weak.} [Quran 4:76]

We advise you to recite Chapter Al-Baqarah in your house as the Prophet, sallallaahu ‘alayhi wa sallam, commanded us to do. He, sallallaahu ‘alayhi wa sallam, said that the devil does not enter the house where this chapter is recited.  [Muslim]

It was also narrated on the authority of Sahl ibn Sa‘d that the Prophet, sallallaahu ‘alayhi wa sallam, said that reciting Chapter Al-Baqarah in a house at night prevents the devil from entering the house for three days.  [Ibn Hibbaan, As-Suyooti: Dha‘eef (weak) and Al-Haythami: Dha‘eef (weak)]

We also advise you to purify your house from anything that causes the presence of devils and prevents angels from entering, such as pictures, statues or musical instruments.  Moreover, you must stop listening to songs, because this is one of the main ways devils enter homes and influence humans.

You should also perform Thikr (mentioning of Allaah) frequently, especially the morning and evening Thikr, Thikr before sleeping, Thikr before leaving and entering the house, Thikr before and after eating, Thikr before entering the bathroom and after leaving it, etc.  By doing this your heart will feel comforted, as Allaah The Almighty Said (what means): {Those who have believed and whose hearts are assured by the remembrance of Allaah. Unquestionably, by the remembrance of Allaah hearts are assured.} [Quran 13:28]

Moreover, you should go to the congregational prayer at the proper time in the mosque, but save the supererogatory prayers to be performed at home.

Also, keep reciting the Al-Mu'awwithatayn (Chapter Al-Falaq and Chapter An-Naas), and the verse of Al-Kursi (the Chair) [Quran 2:255]

All this will expel the devil and evil Jinn, if Allaah wills, and it will even make them fear you.

Allaah Knows best.