It is narrated from Ibn Umar (may Allah be pleased with them both) that Umar (may Allah be pleased with him) said: O Messenger of Allah! I have acquired such wealth from Khaybar that I have never obtained any wealth better or more valuable to me than this. So the Messenger of Allah (peace and blessings be upon him) said: "If you wish, keep the ownership of the garden and dedicate its produce in the way of Allah." So Umar ibn Al-Khattab (may Allah be pleased with him) gave it in charity, then Ibn Umar (may Allah be pleased with them both) described the manner of his charity.
Hadith Referenceمسند الإمام الشافعي / كتاب الوقف والعمرى والرقبى / 1062
Hadith Takhrijصحيح من غيـر هـذا الـطـريـق اخرجه البخارى، الشروط ، باب الشروط في الوقف (2737) ومسلم، الوصية، باب الوقف (1632)۔