Maliks Muwatta Book 36, Hadith Number 43.

Malik related to me from Ibn Shihab from Abu Salama ibn Abd ar-Rahman ibn Awf from Jabir ibn Abdullah al-Ansari that the Messenger of Allah, may Allah bless him and grant him peace, said, “If someone is given a life pension, for him and his posterity, it belongs to the person to whom it has been given. It never reverts to the one who gave it because he gave a gift and the rules of inheritance apply to it.”