Musannaf Ibn Abi Shayba 13:2671

Abu Bakr narrated to us, he said: Muhammad ibn Bishr narrated to us, he said: Hajjaj ibn Abi Uthman narrated to us, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "O assembly of the Ansar, hold onto your wealth for yourselves and do not grant it as *umra* (life-tenancy). For whoever is granted something as *umra*, it belongs to the one to whom it was granted."