Surah Al-Mai'dah (The Spread Table), Verse 51

یٰۤاَیُّهَا الَّذِیْنَ اٰمَنُوْا لَا تَتَّخِذُوا الْیَهُوْدَ وَالنَّصٰرٰۤی اَوْلِیَآءَ بَعْضُهُمْ اَوْلِیَآءُ بَعْضٍ وَمَنْ یَّتَوَلَّهُمْ مِّنْكُمْ فَاِنَّهٗ مِنْهُمْ اِنَّ اللّٰهَ لَا یَهْدِی الْقَوْمَ الظّٰلِمِیْنَ ۟

Yaaa aiyuhal lazeena aamanoo laa tattakhizul Yahooda wan nasaaraaa awliyaaa'; ba'duhum awliyaaa'u ba'd; wa mai yatawallahum minkum fa innahoo minhum; innal laaha laa yahdil qawmaz zaalimeen

“O ye who believe! take not the Jews and the Christians for your friends and protectors: They are but friends and protectors to each other. And he amongst you that turns to them (for friendship) is of them. Verily Allah guideth not a people unjust.”

Quran 5:51 (Yusuf Ali Translation)