Surah Ali 'Imran — Ayah 100 (3:100)
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓاْ إِن تُطِيعُواْ فَرِيقٗا مِّنَ ٱلَّذِينَ أُوتُواْ ٱلۡكِتَٰبَ يَرُدُّوكُم بَعۡدَ إِيمَٰنِكُمۡ كَٰفِرِينَ ١٠٠
English translation (Saheeh International)
O you who have believed, if you obey a party of those who were given the Scripture, they would turn you back, after your belief, [to being] unbelievers.
Brief commentary
O you who have faith in Allah and follow His Prophet, if you follow a group of the People of the Scripture, from the Jews or the Christians, in what they say, and accept their opinion in what they claim, then you will return to disbelief after your faith because of their envy and their misguidance.