Rifa’ah bin Shaddad says: One day I was standing by the bedside of Mukhtar. When it became clear to me that he was a liar, by Allah! I intended to draw my sword and strike off his neck. But then I remembered a hadith which Hazrat Amr bin Al-Hamq (may Allah be pleased with him) had narrated to me, that I heard the Noble Prophet (peace and blessings be upon him) say: Whoever grants safety to a Muslim for his life and then kills him afterwards, a banner of treachery will be given to him on the Day of Resurrection.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 23701