Abu Dawud Book 34, Hadith Number 4499.

Chapter : If a man gives another poison to drink or eat will retaliation be taken on him or not.

Narated By Umm Mubashshir : Umm Mubashshir said to the Prophet (PBUH) during the sickness of which he died: What do you think about your illness, Apostle of Allah (PBUH)? I do not think about the illness of my son except the poisoned sheep of which he had eaten with you at Khaybar. The Prophet (PBUH) said: And I do not think about my illness except that. This is the time when it cut off my aorta.

Abu Dawud said: Sometimes ‘Abd al-Razzaq transmitted this tradition, omitting the link of the Companion, from Ma’rnar, from al-Zuhri, from the Prophet (may peace be upon him), and sometimes he transmitted it from al-Zuhri from ‘Abd al -Rahman b. Ka’b b. Malik. ‘Abd al-Rahman mentioned that Ma’mar sometimes trans-mitted the tradition in a mursal form (omitting the link of the Companion), and they recorded it, and sometimes he transmitted it in a mursal form (with a perfect chain) and they recorded it. And all this is correct with us. ‘Abd al-Razzaq said: When Ibn al-Mubarak came to Ma’mar, he transmitted the traditions in a musnad form (with a perfect chain) which he transmitted as mauquf traditions (statements of the Companions and not of the Prophet).