Sahih Muslim
The Book of Jihad and Expedition (Kitab Al-Jihad wal-Siyar)
Book Number: 019 / Hadith Number: 4307
It has been narrated on the authority of Abdullah that the Messenger of Allah (may peace be upon him) said: There will be for every perfidious person on the Day of Judgment a flag by which he will be recognised. It will be announced: Here is the breach of faith of so and so.