Whoever kills a man after giving him assurance, a banner of treachery will be raised for him on the Day of Resurrection

It is narrated from Amir bin Shaddad: I was well acquainted with the secrets of the Liar (al-Kadhdhab). I used to go to him with my sword. One day I went to him and he said: By Allah! You have come to me just as Jibril has risen from this chair. I reached for the hilt of my sword and thought of cutting off his head, but then I remembered the hadith that Sayyiduna Amr bin al-Hamiq (may Allah be pleased with him) narrated to us, saying: I heard the Messenger of Allah (peace and blessings be upon him) say: "When a man trusts another (gives him safety), and then that one kills him, a banner of treachery will be raised for him on the Day of Resurrection."
This hadith has an authentic chain (sahih al-isnad), but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "The blood of a person from the people of the Qiblah is not lawful except in three cases: one who killed, so he is killed in retaliation; the married adulterer; and the one who leaves the community (jama'ah)."
This hadith has an authentic chain (sahih al-isnad) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it with this wording.

It is narrated from the Mother of the Believers, Sayyidah Aishah (may Allah be pleased with her), that she said: "Shedding the blood of anyone from the people of the Qiblah is not lawful except in three cases: a man who killed someone, so he is killed in retaliation for him; the married adulterer; and the one who separates from the community (jama'ah)."

A similar narration is reported from Sayyidah Aishah (may Allah be pleased with her) from the Prophet (peace and blessings be upon him).