يٰٓاَيُّهَا الَّذِيْنَ اٰمَنُوْا لَا تَتَّخِذُوْا بِطَانَةً مِّنْ دُوْنِكُمْ لَا يَأْلُوْنَكُمْ خَبَالًاۗ وَدُّوْا مَا عَنِتُّمْۚ قَدْ بَدَتِ الْبَغْضَاۤءُ مِنْ اَفْوَاهِهِمْۖ وَمَا تُخْفِيْ صُدُوْرُهُمْ اَكْبَرُ ۗ قَدْ بَيَّنَّا لَكُمُ الْاٰيٰتِ اِنْ كُنْتُمْ تَعْقِلُوْنَ ( آل عمران: ١١٨ )
Yaaa ayyuhal lazeena aamanoo laa tattakhizoo bitaanatam min doonikum laa yaaloonakum khabaalanw waddoo maa 'anittum qad badatil baghdaaa'u min afwaahihim; wa maa tukhfee sudooruhum akbar; qad baiyannaa lakumul Aayaati in kuntum ta'qiloon (ʾĀl ʿImrān 3:118)
O you who have believed, do not take as intimates those other than yourselves [i.e., believers], for they will not spare you [any] ruin. They wish you would have hardship. Hatred has already appeared from their mouths, and what their breasts conceal is greater. We have certainly made clear to you the signs, if you will use reason. (Ali 'Imran  : 118)
1 Mufti Taqi Usmani
O you who believe, do not take anyone as an insider but those from among your own selves. They would spare no effort to do you mischief. They want you to be in trouble. Malice has come out of their mouths while what is concealed in their hearts is still worse. We have made the signs clear to you, if only you understand.