Surah Aali Imran (The Family of Imran), Verse 118

یٰۤاَیُّهَا الَّذِیْنَ اٰمَنُوْا لَا تَتَّخِذُوْا بِطَانَةً مِّنْ دُوْنِكُمْ لَا یَاْلُوْنَكُمْ خَبَالًا وَدُّوْا مَا عَنِتُّمْ قَدْ بَدَتِ الْبَغْضَآءُ مِنْ اَفْوَاهِهِمْ وَمَا تُخْفِیْ صُدُوْرُهُمْ اَكْبَرُ قَدْ بَیَّنَّا لَكُمُ الْاٰیٰتِ اِنْ كُنْتُمْ تَعْقِلُوْنَ ۟

Yaaa ayyuhal lazeena aamanoo laa tattakhizoo bitaanatam min doonikum laa ya'loonakum khabaalanw waddoo maa 'anittum qad badatil baghdaaa'u min afwaahihim; wa maa tukhfee sudooruhum akbar; qad baiyannaa lakumul Aayaati in kuntum ta'qiloon

“O ye who believe! Take not into your intimacy those outside your ranks: They will not fail to corrupt you. They only desire your ruin: Rank hatred has already appeared from their mouths: What their hearts conceal is far worse. We have made plain to you the Signs, if ye have wisdom.”

Quran 3:118 (Yusuf Ali Translation)