Sunan an-Nasa'i 3728
سنن النسائي#3728SahihAbdul-Karim narrated from 'Ata', who said:"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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih Lighairihi
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 34:10