Musnad Ahmad 33:118

Waki' narrated to us, from Sufyan, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Retain your wealth for yourselves and do not grant it as *'umra* (life-tenure gifts). For whoever is granted an *'umra*, it becomes the path of inheritance."