Sunan Ibn Majah 173
سنن ابن ماجه#173SahihIt was narrated that Ibn Awfa said:"The Messenger of Allah said: 'The Khawarij are the dogs of Hell
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautHasan
Zubair Ali ZaiHasan