Muhammad bin 'Abdul A'la محمد بن عبد الأعلى · 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."

"I heard Qatadah narrating from 'Ata', from Jabir that the Prophet said: 'Umra 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.'"