Sahih Muslim 101
Sahih Muslim · Book 1: The Book of Faith · The Saying of the prophet (saws): "Whoever deceives us is not one of us."
It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) observed:
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ ، حَدَّثَنَا يَعْقُوبُ، - وَهُوَ ابْنُ عَبْدِ الرَّحْمَنِ الْقَارِيُّ ح وَحَدَّثَنَا أَبُو الأَحْوَصِ، مُحَمَّدُ بْنُ حَيَّانَ حَدَّثَنَا ابْنُ أَبِي حَازِمٍ ، كِلاَهُمَا عَنْ سُهَيْلِ بْنِ أَبِي صَالِحٍ ، عَنْ أَبِيهِ ، عَنْ أَبِي هُرَيْرَةَ ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ حَمَلَ عَلَيْنَا السِّلاَحَ فَلَيْسَ مِنَّا وَمَنْ غَشَّنَا فَلَيْسَ مِنَّا " .
He who took up arms against us is not of us and he who acted dishonestly towards us is not of us.