Sunan an-Nasa'i, Volume 4, Book 33, Hadith 3747 (DarusSalam) ⓘ
Ma'mar narrated from Ibn Tawus, from his father, from Hujr Al-Madari, from Zaid bin Thabit, from Prophet, who said: "'Umra (a gift given for life) is permissible."
أَخْبَرَنَا مُحَمَّدُ بْنُ عُبَيْدٍ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ الْمُبَارَكِ، عَنْ مَعْمَرٍ، عَنِ ابْنِ طَاوُسٍ، عَنْ أَبِيهِ، عَنْ حُجْرٍ الْمَدَرِيِّ، عَنْ زَيْدِ بْنِ ثَابِتٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْعُمْرَى جَائِزَةٌ " .
also referenced under: Hadith 3717 (Reference) & Book 33, Hadith 12 (In-Book)