Messenger of Allah ﷺ said, "A flag will be fixed on the Day of Resurrection for every betrayer, and it will be announced (publicly in front of everybody), 'This is the betrayal (perfidy) so-and-so, the son of soand- so." (Using translation from Bukhārī 6178)
"إِنَّ الْغَادِرَ يُنْصَبُ له لِوَاءٌ يَوْمَ الْقِيَامَةِ فَيُقَالُ: أَلَا هَذِه غَدْرَةُ فُلَانِ بنِ فُلانٍ".