The Messenger of Allah ﷺ as saying: If anyone has property given him in life-tenancy for the use of himself and his descendants, it belongs to the one to whom it is given and does not return to the one who gave it, because he gave a gift which may be inherited. (Using translation from Abū Dāʾūd 3553)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ «أَيُّمَا رَجُلٍ أُعْمِرَ عُمْرَى لَهُ وَلِعَقِبِهِ فَإِنَّهَا لِلَّذِي يُعْطَاهَا لَا تَرْجِعُ إِلَى الَّذِي أَعْطَاهَا؛ لِأَنَّهُ أَعْطَى عَطَاءً وَقَعَتْ فِيهِ الْمَوَارِيثُ»