It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that when Khaybar was conquered, the Jews requested the Messenger of Allah (peace and blessings be upon him) to let them stay there on the condition that they would work the land of Khaybar and receive half of the fruit and grain it produced. The Messenger of Allah (peace and blessings be upon him) said: "We let you stay on that condition, but only for as long as we wish." They remained on that condition during the time of the Messenger of Allah (peace and blessings be upon him), of Sayyiduna Abu Bakr (may Allah be pleased with him) and for part of the time of Sayyiduna Umar (may Allah be pleased with him). Half of Khaybar was divided into various shares, and the Messenger of Allah (peace and blessings be upon him) used to take the khums (one-fifth) from it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المساقاة / 11625