Sunan an-Nasa'i, Book 33, Hadith 8 (In-Book)

(A different chain) from Hajjaj, from Abu Az-Zubair, from Tawus, from Ibn 'Abbas, who said: "'Umra and Ruqba are not proper. Whoever gives something on the basis of 'Umra or Ruqba, it belongs to the one to whom he gave it on that basis, both during his lifetime and after his death." Hanzalah narrated it in Mursal form.

أَخْبَرَنَا أَحْمَدُ بْنُ سُلَيْمَانَ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، قَالَ حَدَّثَنَا حَجَّاجٌ، عَنْ أَبِي الزُّبَيْرِ، عَنْ طَاوُسٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ لاَ تَصْلُحُ الْعُمْرَى وَلاَ الرُّقْبَى فَمَنْ أَعْمَرَ شَيْئًا أَوْ أَرْقَبَهُ فَإِنَّهُ لِمَنْ أُعْمِرَهُ وَأُرْقِبَهُ حَيَاتَهُ وَمَوْتَهُ ‏.‏ أَرْسَلَهُ حَنْظَلَةُ ‏.‏

sunnah.com