Musnad Ahmad 938:8

Isma'il narrated to us, Ayyub narrated to us, from Nafi', who said: Ibn Umar said: Zayd ibn Thabit narrated to me: "That the Messenger of Allah (peace and blessings of Allah be upon him) granted a concession regarding the sale of 'Araya (dates on the palm tree) for their estimated value (in dried dates)."