I heard the Messenger of Allah ﷺ say, "Whoever grants someone a property as a lifelong gift for him and his descendants has, by his very words, surrendered his right to it. It belongs to the one to whom it was granted and to his descendants."
حدثنا محمد بن رمح أنبأنا الليث بن سعد عن ابن شهاب عن أبي سلمة
سمعت رسول الله ﷺ يقول من أعمر رجلا عمرى له ولعقبه فقد قطع قوله حقه فيها فهي لمن أعمر ولعقبه
Bukhari narrated it in "Gifts, Their Merit, and Encouragement Toward Them," chapter on what has been said regarding umra and ruqba grants, hadith no. 2625, from the hadith of Abu Salama, transmitting it in this manner. Muslim also narrated it in "Gifts," chapter on umra, hadith no. 1625, from Muhammad bin Rumh, transmitting it in this manner.