It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with both of them) that when the Prophet (peace and blessings of Allah be upon him) arrived in Madinah, he found out that the people there used to make transactions of dates on credit for one year or two or three years. The Prophet (peace and blessings of Allah be upon him) said: "Whoever makes a Salam sale in dates, he should specify its measure and specify its weight."