Sahih Muslim 1067
Sahih Muslim · Book 12: The Book of Zakat · The Khawarij are the most evil of people and of all creation
Abu Dharr reported Allah's Messenger (ﷺ) as saying:
حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ ، حَدَّثَنَا سُلَيْمَانُ بْنُ الْمُغِيرَةِ ، حَدَّثَنَا حُمَيْدُ بْنُ هِلاَلٍ ، عَنْ عَبْدِ اللَّهِ بْنِ الصَّامِتِ ، عَنْ أَبِي ذَرٍّ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ بَعْدِي مِنْ أُمَّتِي - أَوْ سَيَكُونُ بَعْدِي مِنْ أُمَّتِي - قَوْمٌ يَقْرَءُونَ الْقُرْآنَ لاَ يُجَاوِزُ حَلاَقِيمَهُمْ يَخْرُجُونَ مِنَ الدِّينِ كَمَا يَخْرُجُ السَّهْمُ مِنَ الرَّمِيَّةِ ثُمَّ لاَ يَعُودُونَ فِيهِ هُمْ شَرُّ الْخَلْقِ وَالْخَلِيقَةِ " . فَقَالَ ابْنُ الصَّامِتِ فَلَقِيتُ رَافِعَ بْنَ عَمْرٍو الْغِفَارِيَّ أَخَا الْحَكَمِ الْغِفَارِيِّ قُلْتُ مَا حَدِيثٌ سَمِعْتُهُ مِنْ أَبِي ذَرٍّ كَذَا وَكَذَا فَذَكَرْتُ لَهُ هَذَا الْحَدِيثَ فَقَالَ وَأَنَا سَمِعْتُهُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم .
Verily there would arise from my Ummah after me or soon after me a group (of people) who would recite the Qur'an, but it would not go beyond their throats, and they would pass clean through their religion just as the arrow passes through the prey, and they would never come back to it. They would be the worst among the creation and the creatures. Ibn Samit (one of the narrators) said: I met Rafi' b. 'Amr Ghifari, the brother of Al-Hakam Ghifari and I said: What is this hadith that I heard from Abu Dharr, i. e. so and so? and then I narrated that hadith to him and said: I heard it from the Messenger of Allah (ﷺ).