It is narrated from Jabir (may Allah be pleased with him) that the Prophet (peace be upon him) said: "Whoever gives something as 'Umra (a type of gift), it belongs to the one to whom it is given."
Hadith Referenceمسند الإمام الشافعي / كتاب الوقف والعمرى والرقبى / 1068
Hadith Takhrijاخرجه مسلم ، الهبات، باب العمرى (1625)۔