Rifa'ah bin Shaddad (may Allah have mercy on him) says: I concealed something under my clothes for al-Mukhtar (the Liar). He says: One day I went in to him, and he said: You have come in, and Jibril (peace be upon him) was standing on this chair before (you came). So I reached for the hilt of my sword. I said (to myself): I will not give him respite until I walk between his head and his body. But then I remembered the hadith of Amr bin al-Hamiq al-Khuza'i (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) had said: "When a person grants someone safety for his life and then kills him, a banner of treachery will be raised for him on the Day of Resurrection." So I held back from him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18423