Yahya related to me from Malik from Ibn Shihab from Said ibn al-Musayyab that the Messenger of Allah, may Allah bless him and granthim peace, said to the jews of Khaybar on the day of the conquest ofKhaybar, "I confirm you in it as long as Allah, the Mighty, theMajestic, establishes you in it, provided that the fruits are dividedbetween us and you." Said continued, "The Messenger of Allah, mayAllah bless him and grant him peace, used to send Abdullah ibn Rawaha,to assess the division of the fruit crop between him and them, and hewould say, 'If you wish, you can buy it back, and if you wish, it ismine.' They would take it."
USC-MSA web (English) reference: Book 33, Hadith 1
Arabic reference: Book 33, Hadith 1391