Sunan an-Nasai Book 34, Hadith 3747

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، عَنِ ابْنِ أَبِي فُدَيْكٍ، قَالَ حَدَّثَنَا ابْنُ أَبِي ذِئْبٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي سَلَمَةَ، عَنْ جَابِرٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَضَى فِيمَنْ أُعْمِرَ عُمْرَى لَهُ وَلِعَقِبِهِ فَهِيَ لَهُ بَتْلَةٌ لاَ يَجُوزُ لِلْمُعْطِي مِنْهَا شَرْطٌ وَلاَ ثُنْيَا ‏.‏ قَالَ أَبُو سَلَمَةَ لأَنَّهُ أَعْطَى عَطَاءً وَقَعَتْ فِيهِ الْمَوَارِيثُ فَقَطَعَتِ الْمَوَارِيثُ شَرْطَهُ ‏.‏

Ibn Abi Dhi'b narrated from Ibn Shihab, from Abu Salamah, from Jabir, that the Messenger of Allah ruled -concerning a person who has been given a lifelong gift ('Umra)- that it belongs to him and to his descendants:"It is undoubtedly his, and it is not permissible for the giver to stipulate any conditions or exceptions." Abu Salamah said: "Because he gave it as a gift and thus, it is subject to the same ruling as the estate, and the condition (that it will revert to the giver on the death of recipient) has become invalid