Khalid bin 'Abdullah al-Tahan خالد بن عبد الله بن عبد الرحمن الطحان · 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.'"

"Any man who gives a lifelong gift to another man, it belongs to him (the recipient) and his descendants. He said: 'I have given it to you and to your descendants so long as any of you are still alive.' So it belongs to the one to whom it was given, and it cannot revert to the first owner, since he has given it as a gift, and as such, it becomes subject to the same ruling as the estate."