Allah will set up a flag for every person guilty of breach of faith on the Day of Judgment, and it will be announced: Look, this is the perfidy of so and so. (Using translation from Muslim 1735c)
قَالَ رَسُولُ اللهِ ﷺ إِنَّ الْغَادِرَ يَنْصِبُ اللهُ لَهُ لِوَاءً يَوْمَ الْقِيَامَةِ فَيُقَالُ أَلَا هَذِهِ غَدْرَةُ فُلَانٍ