Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "Do not give anything as ruqba, do not give anything as umra; if you do so, then it will be counted as umra and marqab." The narrator says: I asked: How will that be? He replied: Umra means that you say: This is yours for your lifetime. And ruqba means that you say: Whichever of you and me dies later, it will go to him.
Imam Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains a narrator, Muthanna bin Sabbah, whom the majority of the imams declared da'if (weak); some said: He is matruk (abandoned); and Yahya bin Ma'in, according to one report, declared him thiqah (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب البيوع / 6779