It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) sent ‘Itab bin Usayd towards Makkah (as a governor) and said:“Do you know where I am sending you? To the people of Allah, who are the people of Makkah. You must prohibit them from these four things: (1) That there be both a sale and a loan in one transaction, (2) two conditions in one sale, (3) profit from something for which a person does not bear the loss, and (4) selling something which is not with you.”