Ibn ‘Umar reported the Apostle of Allaah ﷺ as saying “A banner will be hoisted for a treacherous man on the Day of Judgment, it will then be announced. This is a treachery of so and so, son of so and so. (Using translation from Abū Dāʾūd 2756)
قَالَ النَّبِيُّ ﷺ «إِنَّ الْغَادِرَ يُنْصَبُ لَهُ لِوَاءٌ يَوْمَ الْقِيَامَةِ» فَيُقَالُ «هَذِهِ غَدْرَةُ فُلَانٍ»