Muwatta Imam Malik (Riwayat Ibn al-Qasim)

It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade (two types of transactions): muzabanah and muhaqalah. Muzabanah is when fresh dates on the trees are bought in exchange for dried dates, and muhaqalah is when land is leased out in exchange for a specified amount of wheat.