al-Hakm bin Nafi', Abu al-Yaman الحكم بن نافع أبو اليمان الحمصي · The Book of 'Umra

"Hold on to your wealth and do not give it on the basis of 'Umra. For whoever is given something on the basis of 'Umra for the rest of his life, it belongs to him for the rest of his life and after his death."