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Surah 6. Al-An'am
Ayah 150
150 قُلْ هَلُمَّ شُهَدَآءَكُمُ ٱلَّذِينَ يَشْهَدُونَ أَنَّ ٱللَّهَ حَرَّمَ هَـٰذَا ۖ فَإِن شَهِدُوا۟ فَلَا تَشْهَدْ مَعَهُمْ ۚ وَلَا تَتَّبِعْ أَهْوَآءَ ٱلَّذِينَ كَذَّبُوا۟ بِـَٔايَـٰتِنَا وَٱلَّذِينَ لَا يُؤْمِنُونَ بِٱلْـَٔاخِرَةِ وَهُم بِرَبِّهِمْ يَعْدِلُونَ
[150] Say to them, "Produce your witness who can testify that Allah has forbidden all this." But, even if they testify, you should not bear witness with them.126 And you should never follow the desires of those, who have treated Our Revelations as false and who do not believe in. the Hereafter and who set up others as equals with their Lord.
126That is, "If they understand the grave responsibility of bearing witness and realize that one should bear witness only to that thing of which one has knowledge, they will never testify that all their self-imposed restrictions on food, that are current among them and according to which such and such a one should not eat such and such a thing, have been prescribed by Allah. But if these people do not realize the responsibility of bearing witness and impudently give false evidence in the name of Allah, you should not associate yourself with their falsehood. As a matter of fact, the real object of challenging them to bear witness is to sort out the righteous people, if any, from among them, and not that you should accept their false testimony. It is expected that in response to the challenge to bear witness, those, who have any righteousness left in them, will consider very seriously whether the rituals they were following were really prescribed by Allah and if they find no proof that these were sent down by Allah, they will give them up."