Slaughtering animals for the jinn and invoking them to fulfill a need
It is obligatory for those who have knowledge of true Tawhid (monotheism) and who know of those people's practices
to explain to them that sacrificing animals for the sake of Jinn, prophets, angels or idols is considered an act of Al-Shirk-ul-Akbar (major form of associating others in worship with Allah) which takes them out of Islam. Likewise, making Du`a' to them to fulfill their needs constitutes an act of Al-Shirk-ul-Akbar and also takes them out of Islam. This is because both sacrificing animals and Du`a' are acts of `Ibadah (worship) which should be offered to Allah Alone. Turning these acts of `Ibadah to anyone other than Allah is a form of Al-Shirk-ul-Akbar. Allah (Exalted be He) says:
Say (O Muhammad صلى الله عليه وسلم): "Verily, my Salât (prayer), my sacrifice, my living, and my dying are for Allâh, the Lord of the ‘Alamîn (mankind, jinn and all that exists).
"He has no partner. And of this I have been commanded, and I am the first of the Muslims."
Say: “Shall I seek a lord other than Allâh, while He is the Lord of all things?"
Allah also says:
"And invoke not besides Allâh, any such that will neither profit you nor harm you, but if (in case) you did so, you shall certainly be one of the Zâlimûn (polytheists and wrong-doers)."
And if Allâh touches you with harm, there is none who can remove it but He, and if He intends any good for you, there is none who can repel His Favour
Moreover, Allah says:
Therefore turn in prayer to your Lord and sacrifice (to Him only).
The Prophet (peace be upon him) said:
Allah has cursed the one who sacrifices to other than Allah…
After becoming aware of the proofs of the Qur'an and Sunnah (whatever is reported from the Prophet) on the prohibition of such practices, in case that they persist in sacrificing animals to Jinn or making Du`a' to them to fulfill their needs; their act is tantamount to Al-Shirk-ul-Akbar for which they will not be excused. They will be called Kafirs (disbelievers).