Mujahid said: Umra means that a man says to another man: It belongs to you so long as you live. When he says that, it belongs to him and to his heirs. Ruqba means that a man says to another: From me and from you.
Hadith Referenceسنن ابي داود / كتاب الإجارة / 3560
Hadith Gradingالألبانی:صحيح الإسناد مقطوع | زبیر علی زئی:إسناده حسن