وَيَحلِفونَ بِاللَّهِ إِنَّهُم لَمِنكُم وَما هُم مِنكُم وَلـٰكِنَّهُم قَومٌ يَفرَقونَ

They swear by God that they are of you, but they are not of you. They are people who cause discord.