Musnad Ahmad 1153:1457

'Abd al-Rahman narrated to us, Sufyan narrated to us, from al-A'mash, from 'Abd Allah ibn Murrah, from Masruq, from 'Abd Allah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) stood among us and said: "By the One besides whom there is no god, the blood of a Muslim man who testifies that there is no god but Allah and that I am the Messenger of Allah is not lawful, except for three individuals: the one who abandons Islam and leaves the community, the married adulterer, and a life for a life." Al-A'mash said: I narrated it to Ibrahim, and he narrated to me, from al-Aswad, from 'A'ishah, the like of it.