What is the definitive ruling on verse 121 of Surat Al-An'am, and is it obligatory to pronounce Allah's name at the time of slaughter? Is it permissible to buy chicken from a person who does not pray and perhaps does not mention Allah's name when slaughtering, and what is the aspect of shirk (polytheism) in the verse, and is it major or minor shirk? What is your advice for resolving this disagreement?

Scholars differ on the ruling of pronouncing the Name of Allah (Tasmiyah) at the time of slaughtering. The preponderant opinion is that it is an absolute condition, so the slaughtered animal is not lawful to eat if the Name of Allah was not pronounced over it, even if by忘れ (inadvertently), due to the words of Allah Almighty: ﴿And do not eat of that upon which the Name of Allah has not been mentioned﴾ [Al-An'am: 121], and due to the words of the Prophet (peace be upon him): «Eat what causes blood to flow and over which the Name of Allah has been mentioned.»

The animal slaughtered by one who abandons prayer is not lawful to eat, even if he pronounced the Name of Allah over it.

As for the aspect of shirk (polytheism) in His (Allah's) words: ﴿And if you obey them, indeed, you are polytheists﴾ [Al-An'am: 121], it refers to obedience in legislation, specifically by making carrion lawful. So, whoever obeys someone who makes the unlawful lawful has made him a partner with Allah in legislation. This shirk in obedience is general to anyone who obeys another in making lawful what is unanimously agreed upon as unlawful, or making unlawful what is unanimously agreed upon as lawful. However, regarding matters of difference, such as what is left without Tasmiyah (pronounced over it), one who follows the opinion of those who deem it lawful is not a polytheist. Whoever eats carrion while believing it to be forbidden is disobedient. As for one who believes the unlawful to be lawful, he is a polytheist. This shirk of obedience is major shirk, and it is supported by verses and hadiths.