When is slaughtering for someone other than Allaah regarded as shirk?
Question

                Is every slaughter that is not done for the sake of Allaah regarded as shirk? Please give details, may Allaah reward you.
Praise be to Allah.
    Slaughter may sometimes be a sacrifice, done to glorify and 
    venerate Allaah, and it may sometimes be done to honour a guest or to 
    provide meat to eat and so on. In the first case, it is not permissible to 
    offer this kind of glorification and veneration to anyone other than Allaah; 
    whoever offers that to anyone other than Allaah has associated someone else 
    with Him and committed major shirk (shirk akbar), and the meat he 
    slaughtered is regarded as maytah (dead meat). But in the second case, this 
    is permissible and may be required, but in all cases it is not permissible 
    to mention the name of anyone other than Allaah when slaughtering the meat, 
    otherwise it becomes maytah (dead meat) which is haraam, so mentioning the 
    name of Allaah when slaughtering the animal is a separate issue from the 
    issue of the purpose of the slaughter. 

    If it is said: how can we differentiate between that which is 
    done to honour a person and that which is an act of worship to someone other 
    than Allaah? The answer is:  that in the case of seeking to draw closer to 
    someone other than Allaah, the intention is not to slaughter the animal for 
    meat, rather the intention is to venerate the one for whom it is slaughtered 
    and to give the meat to other people, such as the one who slaughters before 
    a chief when he returns from a journey and so on, then he gives the meat to 
    other people to eat it. This is what some people used to do in the past, and 
    this sacrifice was only done in order to venerate the chief, so it comes 
    under the heading of major shirk. 

    Shaykh Ibn ‘Uthaymeen said: 

    Slaughter means killing by shedding the blood in a specific 
    manner, which is done in several ways: 

    1 – That which is done as an act of worship with the 
    intention of venerating the one for whom the sacrifice is done and humbling 
    oneself before him and drawing closer to him. This may only be done for 
    Allaah in the manner prescribed by Allaah. Doing this for anyone other than 
    Allaah is major shirk. The evidence for that is the verse in which Allaah 
    says (interpretation of the meaning): 

    “Say (O Muhammad): Verily, my Salaah (prayer), my 
    sacrifice, my living, and my dying are for Allaah, the Lord of the ‘Aalameen 
    (mankind, jinn and all that exists)”

    [al-An’aam 6:162]
2 – That which is done to 
    honour a guest or for a wedding feast and the like. This is something which 
    is enjoined and is either obligatory or mustahabb (encouraged), because the 
    Prophet SAWS (peace and blessings of Allaah be upon him) said: “Whoever 
    believes in Allaah and the Last Day, let him honour his guest.” And he SAWS 
    (peace and blessings of Allaah be upon him) said to ‘Abd al-Rahmaan ibn 
    ‘Awf: “Give a wedding feast even if it is with only one sheep.” 

    3 – That which is done to provide food or to sell the meat 
    and so on. This comes under the heading of that which is permissible and the 
    basic principle is that it is allowed, because Allaah says (interpretation 
    of the meaning): 

    “Do they not see that We have created for them of what Our 
    Hands have created, the cattle, so that they are their owners.
72. And We have subdued 
    them unto them so that some of them they have for riding and some they eat”

    [Ya-Seen 36:71-72]
and it may be required or 
    forbidden, depending on what it is a means to. 

    Sharh al-Usool al-Thalaathah in
    Majmoo’ al-Fataawa, 6/62. 

    It says in Mawaahib al-Jaleel: With regard to 
    slaughtering sacrifices to idols, there is no dispute that it is haraam, 
    because this is something that is sacrificed to something other than Allaah. 
    (3/213). 

    It says in Radd al-Muhtaar (6/309): 
Slaughtering an animal 
    for the arrival of prominent figure is forbidden, whilst slaughtering an 
    animal to honour a guest is permissible. Then he said: The difference is 
    that if he offers some of the meat to the prominent figure, then the 
    slaughter is for the sake of Allaah and the benefit is for the guest or the 
    wedding feast or the purpose of making money (by selling the meat), but if 
    he does not offer any of it to the prominent figure and he gives it to 
    others, then it was done to venerate someone other than Allaah, so it is 
    haraam. 

    It says in al-Majmoo’: It is not permissible for the 
    one who is slaughtering the animal to say “In the name of Muhammad” or “In 
    the name of Allaah and the name of Muhammad.” Rather it is the right of 
    Allaah that slaughtering should be done only in His name and vows should be 
    made only in His name, and prostration should be done only to Him, and no 
    created being should be associated with Him in that. Al- Ghazaali said in 
    al-Waseet that it is not permissible to say, “In the name of Allaah and 
    Muhammad the Messenger of Allaah (S).” because this is shirk. (8/384). 
Shaykh Ibn ‘Uthaymeen was 
    asked about the ruling on offering a sacrifice to someone other than Allaah, 
    and whether it is permissible to eat that meat. He replied: Offering a 
    sacrifice to someone other than Allaah is major shirk, because offering a 
    sacrifice is an act of worship, as Allaah says (interpretation of the 
    meaning): 

    “Therefore turn in prayer to your Lord and sacrifice (to Him 
    only)”

    [al-Kawthar 108:2]

    “Say (O Muhammad): Verily, my Salaah (prayer), my 
    sacrifice, my living, and my dying are for Allaah, the Lord of the ‘Aalameen 
    (mankind, jinn and all that exists)”

    [al-An’aam 6:162]

    So whoever offers a sacrifice to anyone other than Allaah is 
    a mushrik whose shirk puts him beyond the pale of Islam – we seek refuge 
    with Allaah – whether he offers that sacrifice to an angel, a Messenger, a 
    Prophet, a caliph, a wali (“saint”) or a scholar. All of that is shirk 
    (associating others in worship with Allaah) which puts one beyond the pale 
    of Islam. People must fear Allaah and not allow themselves to fall into that 
    shirk of which Allaah says (interpretation of the meaning): 
“Verily, whosoever sets 
    up partners (in worship) with Allaah, then Allaah has forbidden Paradise to 
    him, and the Fire will be his abode. And for the Zaalimoon (polytheists and 
    wrongdoers) there are no helpers”

    [al-Maa’idah 5:72]

    Eating from this meat is haraam, because it has been 
    sacrificed to someone other than Allaah, and everything that is sacrificed 
    to someone other than Allaah or slaughtered on an altar is haraam, as Allaah 
    says in Soorat al-Maa’idah (interpretation of the meaning): 
“Forbidden to you (for 
    food) are: Al‑Maitah (the dead animals — cattle — beast not slaughtered), 
    blood, the flesh of swine, and that on which Allaah’s Name has not been 
    mentioned while slaughtering (that which has been slaughtered as a sacrifice 
    for others than Allaah, or has been slaughtered for idols) and that which 
    has been killed by strangling, or by a violent blow, or by a headlong fall, 
    or by the goring of horns — and that which has been (partly) eaten by a wild 
    animal — unless you are able to slaughter it (before its death) ‑ and that 
    which is sacrificed (slaughtered) on An‑Nusub (stone‑altars)”
[al-Maa'idah 5:3] 

    These sacrifices which are slaughtered for anyone other than 
    Allaah come under the heading of haraam food which we are not permitted to 
    eat. 

    Shaykh Ibn ‘Uthaymeen was asked about the ruling on offering 
    sacrifices to anyone other than Allaah. 

    He replied: 

    We have stated elsewhere that Tawheed means devoting worship 
    only to Allaah – may He be exalted – and not worshipping anyone other than 
    Allaah with any kind of act of worship. It is well known that offering 
    sacrifices is a kind of worship by means of which a person seeks to draw 
    closer to his Lord, because Allaah has enjoined it in the verse 
    (interpretation of the meaning): 

    “Therefore turn in prayer to your Lord and sacrifice (to 
    Him only)”

    [al-Kawthar 108:2]

    Every act by means of which a person seeks to draw closer (to 
    his Lord) is an act of worship. So if a person offers a sacrifice to someone 
    other than Allaah as an act of veneration and humility, seeking thereby to 
    draw closer to him, as he seeks to draw closer to his Lord and venerate Him, 
    then he is a mushrik who associates others in worship with Allaah. And if he 
    is a mushrik, then Allaah has stated that He has forbidden Paradise to the 
    mushrik and his abode is Hell. 

    Based on that, we say that what some people do, offering 
    sacrifice to graves – the graves of those whom they claim to be awliya’ 
    (“saints”) – is shirk which puts them beyond the pale of Islam. Our advice 
    to these people is to repent to Allaah from their actions and to make their 
    sacrifices for Allaah alone, and their prayer and fasting for Allaah alone; 
    if they do that, He will forgive for them what they did before, as Allaah 
    says (interpretation of the meaning): 

    “Say to those who have disbelieved, if they cease (from 
    disbelief), their past will be forgiven”

    [al-Anfaal 8:38]
Majmoo’ al-Fataawa 
    2/148. 

    For more information see al-Qawl al-Mufeed ‘ala Kitaab al-Tawheed, 1/215; Tayseer al-‘Azeez al-Hameed, 1/155; 
    al-Durar al-Sanniyyah min al-Ajwabah al-Najdiyyah, 1/428.