Hisham bin Abi 'Abdullah al-Dastawa'i هشام بن أبي عبد الله الدستوائي · The Book of 'Umra

"The Messenger of Allah forbade 'Umra and Ruqba." I said: "What is Ruqba?" He said: "When one man says to another: 'This belongs to you for the rest of your life.' But if you do that, it is permissible."

"The Messenger of Allah said: 'Umra (a lifelong gift) belongs to the one to whom it was given; it belongs to him and to his heirs, and is inherited by those among his descendants who inherit from him.'"

"Abu Salamah bin 'Abdur-Rahman narrated to me, that Jabir told him: 'The Messenger of Allah ruled that whoever gives a lifelong gift to a man, it belongs to him and to his heirs. It belongs to the one to whom it was given, on the basis of 'Umra. It will be inherited from its recipient according to Allah's (injunctions on) inheritance and its rights.'"