It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whichever man gives someone a lifelong grant ('umra) for him and his heirs, it belongs to the one to whom it was given; it does not return to the one who gave it, because he has given a gift in which inheritance has come into effect."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11960