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: "Whoever is given something as a lifelong grant ('umra), it belongs to him and his heirs. Whoever is his heir will inherit it from him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11968