Musnad Abu Ya'la al-Mawsili 109:94

Hajjaj narrated to us, Ya'qub narrated to us, my father narrated to us, from Salih, from Ibn Shihab, that Abu Salamah ibn 'Abd al-Rahman informed him, from Jabir ibn 'Abd Allah, that the Messenger of Allah (may Allah bless him and grant him peace) decreed: "Any man who grants another a life-tenure (*'umra*) for him and his descendants, saying, 'I give it to you and your descendants as long as one of you remains,' then it belongs to the one to whom it was given. It does not return to its owner, because he gave a gift in which the laws of inheritance have taken effect."