It is narrated from Sayyiduna Jabir bin Abdullah Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever gives someone an 'Umra (a gift for life) for him and his heirs, then that 'Umra becomes his, and the giver cannot take it back." (Because he has given something in which inheritance has become established.)