Narrated by Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): When the Noble Prophet (peace and blessings be upon him) arrived in Madinah Munawwarah, the people used to engage in forward sales (salam) of dates for two or three years. The Prophet (peace and blessings be upon him) said: Whoever wishes to do a forward sale should do so with a specified measure, a determined weight, and for a fixed period.