The Book of Gifts
Ṣaḥīḥ Muslim 4190
أَيُّمَا رَجُلٍ أَعْمَرَ رَجُلاً عُمْرَى لَهُ وَلِعَقِبِهِ فَقَالَ قَدْ أَعْطَيْتُكَهَا وَعَقِبَكَ مَا بَقِيَ مِنْكُمْ أَحَدٌ . فَإِنَّهَا لِمَنْ أُعْطِيَهَا . وَإِنَّهَا لاَ تَرْجِعُ إِلَى صَاحِبِهَا مِنْ أَجْلِ أَنَّهُ أَعْطَى عَطَاءً وَقَعَتْ فِيهِ الْمَوَارِيثُ
ayyumā rajulin aʿmara rajulan ʿumrā lah waliʿaqibihi faqāla qad aʿṭaytukahā waʿaqibaka mā baqiya minkum aḥadun . fa-innahā liman uʿṭiyahā . wa-innahā lā tarjiʿu ilā ṣāḥibihā min ajli annah aʿṭā ʿaṭāʾan waqaʿat fīhi al-mawārīthu
Transliteration generated from the Arabic vowel marks
The full narration
Jabir b. 'Abdullah al-Ansari (Allah be pleased with him) said:Allah's Messenger (ﷺ) said: Whoever a person conferred Umra (life grant) upon a person and he says: I confer upon you this and upon your descendants and anyone who survives you, and that becomes his possession and that of his posterity. It would become (a permanent possession) of those who were conferred upon this gift, and it would not return to its owner (donor), for he gave that as a gift in which accrued the right of inheritance
Source
Ṣaḥīḥ Muslim · 4190