Musnad Ahmad 33:158

Ishaq narrated to us, Hisham narrated to us, from Yahya ibn Abi Kathir, from Abu Salamah ibn Abd al-Rahman, from Jabir ibn Abdullah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The 'Umra (gift of a house for life) belongs to the one to whom it was gifted."