Musnad Ahmad 31:587

'Abd al-Rahman narrated to us, Malik narrated to us, from Dawud ibn al-Husayn, from Abu Sufyan, from Abu Sa'id al-Khudri, that the Messenger of Allah (peace and blessings of Allah be upon him) forbade *al-muzabanah* and *al-muhaqalah*. *Al-muzabanah* is the purchasing of fruit on the tops of palm trees with dates by measure. *Al-muhaqalah* is [the practice] regarding the renting of land.