It is well known through the legal evidence from the Qur'an and the Sunnah (whatever is reported from the Prophet) that drawing closer to other than Allah, whether Awliya' (pious people), Jinn (creatures created from fire), idols, or others by slaughtering animals for their sake is considered Shirk (associating others with Allah in His Divinity or worship). It is an act of Jahiliyyah (preIslamic time of ignorance) committed by the Mushriks (those who associate others with Allah in His Divinity or worship).
Say (O Muhammad ﺻﻠﻰ ﺍﷲ 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."
Sacrifice refers to the act of slaughtering animals. Allah (Glorified be He) makes it clear that slaughtering animals for other than Him is considered Shirk, exactly like offering Salah (Prayer) to other than Allah.
Verily, We have granted you (O Muhammad ﺻﻠﻰ ﺍﷲ ﻋﻠﻴﻪ ﻭﺳﻠﻢ) AlKauthar (a river in Paradise). Therefore turn in prayer to your Lord and sacrifice (to Him only).
In this Surah (Qur'anic chapter), Allah (Glorified be He) asked His Prophet to offer Salah and slaughter animals for His Sake, unlike the Mushriks who offer Salah and slaughtered animals for other than Allah.
And your Lord has decreed that you worship none but Him.
And they were commanded not, but that they should worship Allâh, and worship none but Him Alone (abstaining from ascribing partners to Him)
There are many Ayahs (Qur'anic verses) in this regard. Slaughtering animals is a form of `Ibadah (worship) that must be sincerely devoted to Allah Alone.
It is mentioned inthe Sahih (authentic) Book of Hadith of Imam Muslim on the authority of Amir AlMu'minin (Commander of the Believers) `Aly ibn Abu Talib (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said: Allah has cursed the one who slaughters a sacrificial animal for other than Allah.
However, if a person supplicates to Allah in the name or virtue of a Waliy (pious person), or a Prophet, this is not considered Shirk, but a Bid`ah (innovation in religion) and one of the means leading to Shirk, according to the Jumhur (dominant majority of scholars). Du`a' (supplication) is a form of `Ibadah, and its formula is a Tawqifiy matter (bound by a religious text and not amenable to personal opinion). Nothing was ever reported from the Prophet (peace be upon him) that proves the permissibility of supplicating to Allah in the name of/by virtue of the status of one of the people, which is known as Tawassul. Thus, it is not permissible for Muslims to innovate a form of Tawassul that was not prescribed by Allah (Glorified be He).
Or have they partners (with Allâh — false gods) who have instituted for them a religion which Allâh has not ordained?
Whoever introduces something into this affair of ours that is not of it, it is to be rejected. (Agreed upon by AlBukhari and Muslim) According to another narration in Sahih Muslim, which was also affirmatively recorded by AlBukhari in his Sahih Book of Hadith and described as Hadith Mu`allaq (a Hadith missing link in the chain of narration, reported directly from the Prophet), the Prophet (peace be upon him) said: Whoever performs any act which is not sanctioned by our affairs (Islamic law), it is to be rejected.
His saying "it is to be rejected" means that it will not be accepted. Muslims must abide by what is prescribed by Allah and beware of the Bid`ahs practiced by people. As for the permissible Tawassul, it is supplicating to Allah by virtue of Allah's Names, Attributes, Tawhid (monotheism), righteous deeds, Iman (belief) in Allah and His Messenger, love of Allah and His Messenger, and such righteous deeds. This also includes Tawassul through the Du`a' and Shafa`ah (intercession) of a living person as authentically reported in Sahih AlBukhari (may Allah be merciful with him) on the authority of Anas (may Allah be pleased with him) who said that `Umar ibn AlKhattab (may Allah be pleased with him) used to perform SalatulIstisqa' (Prayer for rain) by asking Allah for rain by virtue of Al`Abbas ibn `AbdulMuttalib at times of drought. He used to say, "O Allah! We used to supplicate to You for rain by virtue of our Prophet and You would send us rain, and now we perform Tawassul to You by virtue of the uncle of our Prophet to send us rain." And Allah sent them rain.
May Allah grant us success!