Musnad Ahmad 33:292

Isma'il narrated to us, from al-Hajjaj al-Sawwaf, from Abu al-Zubayr, if Allah wills, from Jabir ibn Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "O assembly of the Ansar, hold onto your wealth and do not grant it as *'umra* (life-tenure). For whoever is granted something as *'umra*, it belongs to the one to whom it was granted, both in his life and in his death."