It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) forbade selling dates that are still on the trees in exchange for harvested dates by measure. It is also narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) forbade the sale and purchase of fruits before they ripen and the contracting of fruits for several years.