It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "If someone gives something to another for a lifetime, it becomes the property of the one to whom it is given. If something is given conditional upon someone's death, it becomes the property of the one to whom it is given. And the one who gives a gift and then takes it back is like one who vomits and then licks it up."