Mishkat al-Masabih 11 Business Transactions كتاب البيوع 246

وَعَنْهُ قَالَ: إِنَّمَا الْعُمْرَى الَّتِي أَجَازَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِن يَقُول: هِيَ لعقبك فَأَمَّا إِذَا قَالَ: هِيَ لَكَ مَا عِشْتَ فَإِنَّهَا ترجع إِلَى صَاحبهَا

He said that the life-tenancy which God’s Messenger allowed was (only that one should say, “It is for you and your descendants.” When he says, “It is yours as long as you live,” it returns to its owner. (Bukhari and Muslim.)