Question Summary:
How authentic is the Hadith of the letter of Rasūlullah Salllahu ‘Alaihi Wa Sallam to the Jinn?

Question Detail:

Is it true that Prophet PBUH wrote a letter to Jinn and if we place a copy that letter in the house the Jinns will leave?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The Hadīth you refer to is narrated by al-Bayhaqī in Dalāil an-Nubuwwah as follows,[1] 
 
بسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ. هَذَا كِتَابٌ مِنْ مُحَمَّدٍ رَسُولِ رَبِّ الْعَالَمِينَ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، إِلَى مَنْ طَرَقَ الدَّارَ مِنَ الْعُمَّارِ، وَالزُّوَّارِ، وَالصَّالِحِينَ، إِلَّا طَارِقًا يَطْرُقُ بِخَيْرٍ يَا رَحْمَنُ. أَمَّا بَعْدُ:فَإِنَّ لَنَا، وَلَكُمْ فِي الْحَقِّ سَعَةً، فَإِنْ تَكُ عَاشِقًا مُولَعًا، أَوْ فَاجِرًا مُقْتَحِمًا أَوْ رَاغِبًا حَقًّا أَوْ مُبْطِلًا، هَذَا كِتَابُ اللهِ تَبَارَكَ وَتَعَالَى يَنْطِقُ عَلَيْنَا وَعَلَيْكُمْ بِالْحَقِّ، إِنَّا كُنَّا نَسْتَنْسِخُ مَا كُنْتُمْ تَعْمَلُونَ، وَرُسُلُنَا يَكْتُبُونَ مَا تَمْكُرُونَ، اتْرُكُوا صَاحِبَ كِتَابِي هَذَا، وَانْطَلِقُوا إِلَى عَبَدَةِ الْأَصْنَامِ، وَإِلَى مَنْ يَزْعُمُ أَنَّ مَعَ اللهِ إِلَهًا آخَرَ.لَا إِلَهَ إِلَّا هُوَ كُلُّ شَيْءٍ هَالِكٌ إِلَّا وَجْهَهُ لَهُ الْحُكْمُ وَإِلَيْهِ ترجعون. يُغْلَبُونَ «حم» لَا يُنْصَرُونَ، حم عسق، تُفَرِّقَ أَعْدَاءَ اللهِ، وَبَلَغَتْ حُجَّةُ اللهِ، وَلَا حَوْلَ ولا قوة إلا بالله فَسَيَكْفِيكَهُمُ اللَّهُ وَهُوَ السَّمِيعُ الْعَلِيمُ.
“In the name of Allah, the Most Compassionate the Most Merciful.
This is a letter from Muhammad the Messenger of the Lord of the worlds, to the dwellers, visitors and pious who enter the house, except those who enter with a good intention, O the Merciful. After praises and salutations, you possess rights. If you are an infatuated lover, intruding transgressor, seeker of a right or a squanderer, then this is a letter from Allah that speaks between us with truth. Verily, we are recording your actions and our angels are writing what you plot. Leave the possessor of this letter and carry on to the worshipers of idols and those who claim that there is a deity besides Allah. There is none worthy of worship besides Him, everything is going to perish save his being. He is the sole authority and to Him you shall be returned. They shall be overcome; Hā Mīm they will not be assisted. O the enemies of Allah disperse. The evidence of Allah has been conveyed; there is no power nor strength except by Allah. Allah will suffice you against them, and He is the Most Hearing the Most Knowing.”
However, many scholars of Hadīth have criticized this Hadīth and have classified it as a fabrication. Hereunder are the remarks of some of the Muhaddithūn,
Ibn al-Jawzi has mentioned a similar narration in his Kitāb al-Mawdhū’āt. He writes,
هَذَا حَدِيث مَوْضُوع بِلَا شكّ وَإِسْنَاده مَقْطُوع.... وَأكْثر رِجَاله مَجَاهِيل لَا يعْرفُون
“Without doubt, this is a fabrication and its chain of transmitters is broken… there is no biographical information available with regards to many of its narrators” [2]
Allāmah al-Dhahabī notes,
وَحِرْزُ أَبِي دُجَانَةَ شَيْءٌ لَمْ يَصِحَّ مَا أَدْرِي مَنْ وَضَعَهُ
“The Hadīth of the incantation of Abū Dujānah is a fabrication, I do not know who fabricated it.”[3]
Allāmah as-Suyūtī comments,
مَوْضُوع: وإِسْنَادُه مَقْطُوع وَأكْثر رِجَاله مَجَاهِيل
“It is a fabrication and its chain of transmission is broken and most of its transmitters are unknown.”[4]
‘Allāmah Fattanī writes,
حَدِيث حرز أبي دُجَانَة فِيهِ مَجَاهِيل قلت أخرجه الْبَيْهَقِيّ فِي الدَّلَائِل :الصغاني «حرز أبي دُجَانَة واسْمه سماك بن خَرشَة» مَوْضُوع.
“The Hadīth pertaining to the incantation of Abū Dujānah contains many unknown transmitter. I say; “Al-Bayhaqī has reported it in his book Dalāil an-Nubuwwah. As-Saghānī has mentioned, “The incantation of Abū Dujānah, his name was Sammāk bin kharshah, is a fabrication.[5]
 
And Allah Ta’āla Knows Best
Muntasir Zaman
Student Darul Iftaa
USA
Checked and Approved by,
Mufti Ebrahim Desai.