It is narrated from Ibn Umar (may Allah be pleased with them both) that when Khaybar was conquered, the Jews asked the Messenger of Allah (peace and blessings be upon him) to let them stay on condition that they would work for half (the produce). The Messenger of Allah (peace and blessings be upon him) said: "I let you stay on that condition for as long as we wish." So they remained on that condition. The fruit of half of Khaybar used to be divided into shares, and the Messenger of Allah (peace and blessings be upon him) used to take the one-fifth of it, and the Messenger of Allah (peace and blessings be upon him) used to give his wives from the one-fifth one hundred wasqs of dates and twenty wasqs of barley. When Sayyiduna Umar (may Allah be pleased with him) intended to expel the Jews, he sent word to the Mothers of the Believers that whichever of you wishes, I will give her date-palms from which I will give a hundred wasqs of dates along with their root and with the water; likewise, from the cultivated land I will also give trees equal to twenty wasqs of barley; and whoever wishes, I will set aside a portion for her from the one-fifth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12949