Sahih Muslim , Book 19, Hadith 4309 (USC-MSA) ⓘ
It is narrated on the authority of Abu Sa'id that the Messenger of Allah said: On the Day of Judgment there will be a flag fixed behind the buttocks of every person guilty of the breach of faith.
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَعُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالاَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، حَدَّثَنَا شُعْبَةُ، عَنْ خُلَيْدٍ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " لِكُلِّ غَادِرٍ لِوَاءٌ عِنْدَ اسْتِهِ يَوْمَ الْقِيَامَةِ " .
also referenced under: Book 32, Hadith 18 (In-Book) & Hadith 1738 (Reference)