Hadith: When Allah gathers the first and the last on the Day of Judgment, a banner will be raised for every traitor, and it will be said: This is the betrayal of so-and-so, the son of so-and-so

عَنِ ابْنِ عُمَرَ رَضيَ اللهُ عنهما قَالَ: قَالَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ:
«إِذَا جَمَعَ اللهُ الْأَوَّلِينَ وَالْآخِرِينَ يَوْمَ الْقِيَامَةِ يُرْفَعُ لِكُلِّ غَادِرٍ لِوَاءٌ، فَقِيلَ: هَذِهِ غَدْرَةُ فُلَانِ بْنِ فُلَانٍ».
[صحيح] - [متفق عليه] - [صحيح مسلم: 1735]

Ibn ‘Umar (may Allah be pleased with him and his father) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said:
"When Allah gathers the first and the last on the Day of Judgment, a banner will be raised for every traitor, and it will be said: This is the betrayal of so-and-so, the son of so-and-so."
[Authentic hadith] - [Narrated by Bukhari & Muslim] - [Sahih Muslim - 1735]

Explanation

The Prophet (may Allah's peace and blessings be upon him) informs that on the Day of Judgment, when Allah Almighty gathers the first and the last for the reckoning, He will set up a sign for every traitor who failed to fulfill a covenant he made, whether with Allah or with people. This sign will expose his betrayal, and he will be called out on that day: This is the betrayal of so-and-so, the son of so-and-so, to expose the evil of his deed before the people of the Gathering.

Benefits from the Hadith

1. The prohibition of treachery, and that it is one of the major sins because of this severe warning associated with it.
2. The betrayal that incurs a severe warning includes anyone who entrusts you with life, honor, secret, or wealth, and you betray him, breaking his trust in your reliability.
3. Al-Qurtubi said: This is an address from him to the Arabs who used to practice, as they used to raise a white banner for loyalty and a black banner for betrayal, to blame and condemn the traitor. The Hadīth implies that something similar will occur for the betrayer, so he will be known for his trait on the Day of Judgment and condemned by the people of the Gathering.
4. Ibn Hajar said: This indicates that people will be called on the Day of Judgment by their fathers, as mentioned in his statement: "This is the betrayal of so-and-so, the son of so-and-so.".